diff --git a/compiler/rustc_target/src/spec/aarch64_apple_darwin.rs b/compiler/rustc_target/src/spec/aarch64_apple_darwin.rs
index ff15f32ca9d..201b13a0f8a 100644
--- a/compiler/rustc_target/src/spec/aarch64_apple_darwin.rs
+++ b/compiler/rustc_target/src/spec/aarch64_apple_darwin.rs
@@ -1,7 +1,7 @@
 use crate::spec::{LinkerFlavor, Target, TargetOptions};
 
 pub fn target() -> Target {
-    let mut base = super::apple_base::opts();
+    let mut base = super::apple_base::opts("macos");
     base.cpu = "apple-a12".to_string();
     base.max_atomic_width = Some(128);
     base.pre_link_args.insert(LinkerFlavor::Gcc, vec!["-arch".to_string(), "arm64".to_string()]);
@@ -19,7 +19,6 @@ pub fn target() -> Target {
         pointer_width: 64,
         data_layout: "e-m:o-i64:64-i128:128-n32:64-S128".to_string(),
         arch: arch.to_string(),
-        target_os: "macos".to_string(),
         target_env: String::new(),
         target_vendor: "apple".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/aarch64_apple_ios.rs b/compiler/rustc_target/src/spec/aarch64_apple_ios.rs
index ce59163e0aa..0c63b9649e8 100644
--- a/compiler/rustc_target/src/spec/aarch64_apple_ios.rs
+++ b/compiler/rustc_target/src/spec/aarch64_apple_ios.rs
@@ -2,13 +2,12 @@ use super::apple_sdk_base::{opts, Arch};
 use crate::spec::{LinkerFlavor, Target, TargetOptions};
 
 pub fn target() -> Target {
-    let base = opts(Arch::Arm64);
+    let base = opts("ios", Arch::Arm64);
     Target {
         llvm_target: "arm64-apple-ios".to_string(),
         pointer_width: 64,
         data_layout: "e-m:o-i64:64-i128:128-n32:64-S128".to_string(),
         arch: "aarch64".to_string(),
-        target_os: "ios".to_string(),
         target_env: String::new(),
         target_vendor: "apple".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/aarch64_apple_tvos.rs b/compiler/rustc_target/src/spec/aarch64_apple_tvos.rs
index a8126c81add..c81a215b7f6 100644
--- a/compiler/rustc_target/src/spec/aarch64_apple_tvos.rs
+++ b/compiler/rustc_target/src/spec/aarch64_apple_tvos.rs
@@ -2,13 +2,12 @@ use super::apple_sdk_base::{opts, Arch};
 use crate::spec::{LinkerFlavor, Target, TargetOptions};
 
 pub fn target() -> Target {
-    let base = opts(Arch::Arm64);
+    let base = opts("tvos", Arch::Arm64);
     Target {
         llvm_target: "arm64-apple-tvos".to_string(),
         pointer_width: 64,
         data_layout: "e-m:o-i64:64-i128:128-n32:64-S128".to_string(),
         arch: "aarch64".to_string(),
-        target_os: "tvos".to_string(),
         target_env: String::new(),
         target_vendor: "apple".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/aarch64_fuchsia.rs b/compiler/rustc_target/src/spec/aarch64_fuchsia.rs
index 65254d5d019..ffaf7453dd6 100644
--- a/compiler/rustc_target/src/spec/aarch64_fuchsia.rs
+++ b/compiler/rustc_target/src/spec/aarch64_fuchsia.rs
@@ -9,7 +9,6 @@ pub fn target() -> Target {
         pointer_width: 64,
         data_layout: "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".to_string(),
         arch: "aarch64".to_string(),
-        target_os: "fuchsia".to_string(),
         target_env: String::new(),
         target_vendor: String::new(),
         linker_flavor: LinkerFlavor::Lld(LldFlavor::Ld),
diff --git a/compiler/rustc_target/src/spec/aarch64_linux_android.rs b/compiler/rustc_target/src/spec/aarch64_linux_android.rs
index caf17fe4e0b..ed859c03209 100644
--- a/compiler/rustc_target/src/spec/aarch64_linux_android.rs
+++ b/compiler/rustc_target/src/spec/aarch64_linux_android.rs
@@ -14,7 +14,6 @@ pub fn target() -> Target {
         pointer_width: 64,
         data_layout: "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".to_string(),
         arch: "aarch64".to_string(),
-        target_os: "android".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/aarch64_pc_windows_msvc.rs b/compiler/rustc_target/src/spec/aarch64_pc_windows_msvc.rs
index 382e2b9272a..6bef3914b4c 100644
--- a/compiler/rustc_target/src/spec/aarch64_pc_windows_msvc.rs
+++ b/compiler/rustc_target/src/spec/aarch64_pc_windows_msvc.rs
@@ -11,7 +11,6 @@ pub fn target() -> Target {
         pointer_width: 64,
         data_layout: "e-m:w-p:64:64-i32:32-i64:64-i128:128-n32:64-S128".to_string(),
         arch: "aarch64".to_string(),
-        target_os: "windows".to_string(),
         target_env: "msvc".to_string(),
         target_vendor: "pc".to_string(),
         linker_flavor: LinkerFlavor::Msvc,
diff --git a/compiler/rustc_target/src/spec/aarch64_unknown_cloudabi.rs b/compiler/rustc_target/src/spec/aarch64_unknown_cloudabi.rs
index ab8e5ad0755..9ad1e5ba36c 100644
--- a/compiler/rustc_target/src/spec/aarch64_unknown_cloudabi.rs
+++ b/compiler/rustc_target/src/spec/aarch64_unknown_cloudabi.rs
@@ -11,7 +11,6 @@ pub fn target() -> Target {
         pointer_width: 64,
         data_layout: "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".to_string(),
         arch: "aarch64".to_string(),
-        target_os: "cloudabi".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/aarch64_unknown_freebsd.rs b/compiler/rustc_target/src/spec/aarch64_unknown_freebsd.rs
index c2dd63e6fc4..5e704567b69 100644
--- a/compiler/rustc_target/src/spec/aarch64_unknown_freebsd.rs
+++ b/compiler/rustc_target/src/spec/aarch64_unknown_freebsd.rs
@@ -9,7 +9,6 @@ pub fn target() -> Target {
         pointer_width: 64,
         data_layout: "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".to_string(),
         arch: "aarch64".to_string(),
-        target_os: "freebsd".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/aarch64_unknown_hermit.rs b/compiler/rustc_target/src/spec/aarch64_unknown_hermit.rs
index 541c485f7ac..5b4c7a2a6f6 100644
--- a/compiler/rustc_target/src/spec/aarch64_unknown_hermit.rs
+++ b/compiler/rustc_target/src/spec/aarch64_unknown_hermit.rs
@@ -9,7 +9,6 @@ pub fn target() -> Target {
         pointer_width: 64,
         data_layout: "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".to_string(),
         arch: "aarch64".to_string(),
-        target_os: "hermit".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Lld(LldFlavor::Ld),
diff --git a/compiler/rustc_target/src/spec/aarch64_unknown_linux_gnu.rs b/compiler/rustc_target/src/spec/aarch64_unknown_linux_gnu.rs
index 58b461bf0d6..99f841989eb 100644
--- a/compiler/rustc_target/src/spec/aarch64_unknown_linux_gnu.rs
+++ b/compiler/rustc_target/src/spec/aarch64_unknown_linux_gnu.rs
@@ -10,7 +10,6 @@ pub fn target() -> Target {
         target_env: "gnu".to_string(),
         data_layout: "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".to_string(),
         arch: "aarch64".to_string(),
-        target_os: "linux".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
         options: TargetOptions {
diff --git a/compiler/rustc_target/src/spec/aarch64_unknown_linux_musl.rs b/compiler/rustc_target/src/spec/aarch64_unknown_linux_musl.rs
index 391672365f9..e3892cc7451 100644
--- a/compiler/rustc_target/src/spec/aarch64_unknown_linux_musl.rs
+++ b/compiler/rustc_target/src/spec/aarch64_unknown_linux_musl.rs
@@ -10,7 +10,6 @@ pub fn target() -> Target {
         target_env: "musl".to_string(),
         data_layout: "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".to_string(),
         arch: "aarch64".to_string(),
-        target_os: "linux".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
         options: TargetOptions {
diff --git a/compiler/rustc_target/src/spec/aarch64_unknown_netbsd.rs b/compiler/rustc_target/src/spec/aarch64_unknown_netbsd.rs
index 08b54edf4fd..c601d847784 100644
--- a/compiler/rustc_target/src/spec/aarch64_unknown_netbsd.rs
+++ b/compiler/rustc_target/src/spec/aarch64_unknown_netbsd.rs
@@ -10,7 +10,6 @@ pub fn target() -> Target {
         pointer_width: 64,
         data_layout: "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".to_string(),
         arch: "aarch64".to_string(),
-        target_os: "netbsd".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/aarch64_unknown_none.rs b/compiler/rustc_target/src/spec/aarch64_unknown_none.rs
index 6f24787d8fa..03b9f53a532 100644
--- a/compiler/rustc_target/src/spec/aarch64_unknown_none.rs
+++ b/compiler/rustc_target/src/spec/aarch64_unknown_none.rs
@@ -24,7 +24,6 @@ pub fn target() -> Target {
     Target {
         llvm_target: "aarch64-unknown-none".to_string(),
         pointer_width: 64,
-        target_os: "none".to_string(),
         target_env: String::new(),
         target_vendor: String::new(),
         data_layout: "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".to_string(),
diff --git a/compiler/rustc_target/src/spec/aarch64_unknown_none_softfloat.rs b/compiler/rustc_target/src/spec/aarch64_unknown_none_softfloat.rs
index b72c1600397..a1fbe5b5819 100644
--- a/compiler/rustc_target/src/spec/aarch64_unknown_none_softfloat.rs
+++ b/compiler/rustc_target/src/spec/aarch64_unknown_none_softfloat.rs
@@ -24,7 +24,6 @@ pub fn target() -> Target {
     Target {
         llvm_target: "aarch64-unknown-none".to_string(),
         pointer_width: 64,
-        target_os: "none".to_string(),
         target_env: String::new(),
         target_vendor: String::new(),
         data_layout: "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".to_string(),
diff --git a/compiler/rustc_target/src/spec/aarch64_unknown_openbsd.rs b/compiler/rustc_target/src/spec/aarch64_unknown_openbsd.rs
index 0f50da1e86c..fefab5df9ae 100644
--- a/compiler/rustc_target/src/spec/aarch64_unknown_openbsd.rs
+++ b/compiler/rustc_target/src/spec/aarch64_unknown_openbsd.rs
@@ -10,7 +10,6 @@ pub fn target() -> Target {
         pointer_width: 64,
         data_layout: "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".to_string(),
         arch: "aarch64".to_string(),
-        target_os: "openbsd".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/aarch64_unknown_redox.rs b/compiler/rustc_target/src/spec/aarch64_unknown_redox.rs
index c2c00af0380..fcdc0e873a0 100644
--- a/compiler/rustc_target/src/spec/aarch64_unknown_redox.rs
+++ b/compiler/rustc_target/src/spec/aarch64_unknown_redox.rs
@@ -9,7 +9,6 @@ pub fn target() -> Target {
         pointer_width: 64,
         data_layout: "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".to_string(),
         arch: "aarch64".to_string(),
-        target_os: "redox".to_string(),
         target_env: "relibc".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/aarch64_uwp_windows_msvc.rs b/compiler/rustc_target/src/spec/aarch64_uwp_windows_msvc.rs
index 143e6651c6b..5b80d55cb0a 100644
--- a/compiler/rustc_target/src/spec/aarch64_uwp_windows_msvc.rs
+++ b/compiler/rustc_target/src/spec/aarch64_uwp_windows_msvc.rs
@@ -10,7 +10,6 @@ pub fn target() -> Target {
         pointer_width: 64,
         data_layout: "e-m:w-p:64:64-i32:32-i64:64-i128:128-n32:64-S128".to_string(),
         arch: "aarch64".to_string(),
-        target_os: "windows".to_string(),
         target_env: "msvc".to_string(),
         target_vendor: "uwp".to_string(),
         linker_flavor: LinkerFlavor::Msvc,
diff --git a/compiler/rustc_target/src/spec/aarch64_wrs_vxworks.rs b/compiler/rustc_target/src/spec/aarch64_wrs_vxworks.rs
index a0ba61ca83e..411814b2206 100644
--- a/compiler/rustc_target/src/spec/aarch64_wrs_vxworks.rs
+++ b/compiler/rustc_target/src/spec/aarch64_wrs_vxworks.rs
@@ -9,7 +9,6 @@ pub fn target() -> Target {
         pointer_width: 64,
         data_layout: "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".to_string(),
         arch: "aarch64".to_string(),
-        target_os: "vxworks".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "wrs".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/android_base.rs b/compiler/rustc_target/src/spec/android_base.rs
index 0824bc30358..1bd5eb6988c 100644
--- a/compiler/rustc_target/src/spec/android_base.rs
+++ b/compiler/rustc_target/src/spec/android_base.rs
@@ -2,6 +2,7 @@ use crate::spec::{LinkerFlavor, TargetOptions};
 
 pub fn opts() -> TargetOptions {
     let mut base = super::linux_base::opts();
+    base.target_os = "android".to_string();
     // Many of the symbols defined in compiler-rt are also defined in libgcc.
     // Android's linker doesn't like that by default.
     base.pre_link_args
diff --git a/compiler/rustc_target/src/spec/apple_base.rs b/compiler/rustc_target/src/spec/apple_base.rs
index 2e3c835c0e5..9532ff4bf50 100644
--- a/compiler/rustc_target/src/spec/apple_base.rs
+++ b/compiler/rustc_target/src/spec/apple_base.rs
@@ -2,7 +2,7 @@ use std::env;
 
 use crate::spec::{LinkArgs, TargetOptions};
 
-pub fn opts() -> TargetOptions {
+pub fn opts(os: &str) -> TargetOptions {
     // ELF TLS is only available in macOS 10.7+. If you try to compile for 10.6
     // either the linker will complain if it is used or the binary will end up
     // segfaulting at runtime when run on 10.6. Rust by default supports macOS
@@ -17,6 +17,7 @@ pub fn opts() -> TargetOptions {
     let version = macos_deployment_target();
 
     TargetOptions {
+        target_os: os.to_string(),
         // macOS has -dead_strip, which doesn't rely on function_sections
         function_sections: false,
         dynamic_linking: true,
diff --git a/compiler/rustc_target/src/spec/apple_sdk_base.rs b/compiler/rustc_target/src/spec/apple_sdk_base.rs
index 1b17c2c278f..092401f1146 100644
--- a/compiler/rustc_target/src/spec/apple_sdk_base.rs
+++ b/compiler/rustc_target/src/spec/apple_sdk_base.rs
@@ -31,7 +31,7 @@ fn link_env_remove(arch: Arch) -> Vec<String> {
     }
 }
 
-pub fn opts(arch: Arch) -> TargetOptions {
+pub fn opts(os: &str, arch: Arch) -> TargetOptions {
     TargetOptions {
         cpu: target_cpu(arch),
         dynamic_linking: false,
@@ -39,6 +39,6 @@ pub fn opts(arch: Arch) -> TargetOptions {
         link_env_remove: link_env_remove(arch),
         has_elf_tls: false,
         eliminate_frame_pointer: false,
-        ..super::apple_base::opts()
+        ..super::apple_base::opts(os)
     }
 }
diff --git a/compiler/rustc_target/src/spec/arm_linux_androideabi.rs b/compiler/rustc_target/src/spec/arm_linux_androideabi.rs
index f94b6c7cbba..a2996655ee4 100644
--- a/compiler/rustc_target/src/spec/arm_linux_androideabi.rs
+++ b/compiler/rustc_target/src/spec/arm_linux_androideabi.rs
@@ -11,7 +11,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "android".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/arm_unknown_linux_gnueabi.rs b/compiler/rustc_target/src/spec/arm_unknown_linux_gnueabi.rs
index c0751eb4b03..495bb5477b6 100644
--- a/compiler/rustc_target/src/spec/arm_unknown_linux_gnueabi.rs
+++ b/compiler/rustc_target/src/spec/arm_unknown_linux_gnueabi.rs
@@ -8,7 +8,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/arm_unknown_linux_gnueabihf.rs b/compiler/rustc_target/src/spec/arm_unknown_linux_gnueabihf.rs
index c218b8a033f..32bed7fe011 100644
--- a/compiler/rustc_target/src/spec/arm_unknown_linux_gnueabihf.rs
+++ b/compiler/rustc_target/src/spec/arm_unknown_linux_gnueabihf.rs
@@ -8,7 +8,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/arm_unknown_linux_musleabi.rs b/compiler/rustc_target/src/spec/arm_unknown_linux_musleabi.rs
index 310a1c96e66..2b99f700a4c 100644
--- a/compiler/rustc_target/src/spec/arm_unknown_linux_musleabi.rs
+++ b/compiler/rustc_target/src/spec/arm_unknown_linux_musleabi.rs
@@ -15,7 +15,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "linux".to_string(),
         target_env: "musl".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/arm_unknown_linux_musleabihf.rs b/compiler/rustc_target/src/spec/arm_unknown_linux_musleabihf.rs
index b48886263fd..e494e08d4e6 100644
--- a/compiler/rustc_target/src/spec/arm_unknown_linux_musleabihf.rs
+++ b/compiler/rustc_target/src/spec/arm_unknown_linux_musleabihf.rs
@@ -15,7 +15,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "linux".to_string(),
         target_env: "musl".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/armebv7r_none_eabi.rs b/compiler/rustc_target/src/spec/armebv7r_none_eabi.rs
index 4f8371b5add..3ba9c1028a7 100644
--- a/compiler/rustc_target/src/spec/armebv7r_none_eabi.rs
+++ b/compiler/rustc_target/src/spec/armebv7r_none_eabi.rs
@@ -9,7 +9,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "E-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "none".to_string(),
         target_env: "".to_string(),
         target_vendor: "".to_string(),
         linker_flavor: LinkerFlavor::Lld(LldFlavor::Ld),
diff --git a/compiler/rustc_target/src/spec/armebv7r_none_eabihf.rs b/compiler/rustc_target/src/spec/armebv7r_none_eabihf.rs
index 6b75e70ce5a..cfa083275e5 100644
--- a/compiler/rustc_target/src/spec/armebv7r_none_eabihf.rs
+++ b/compiler/rustc_target/src/spec/armebv7r_none_eabihf.rs
@@ -9,7 +9,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "E-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "none".to_string(),
         target_env: String::new(),
         target_vendor: String::new(),
         linker_flavor: LinkerFlavor::Lld(LldFlavor::Ld),
diff --git a/compiler/rustc_target/src/spec/armv4t_unknown_linux_gnueabi.rs b/compiler/rustc_target/src/spec/armv4t_unknown_linux_gnueabi.rs
index cc7f1bb28d1..5af602c4714 100644
--- a/compiler/rustc_target/src/spec/armv4t_unknown_linux_gnueabi.rs
+++ b/compiler/rustc_target/src/spec/armv4t_unknown_linux_gnueabi.rs
@@ -7,7 +7,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/armv5te_unknown_linux_gnueabi.rs b/compiler/rustc_target/src/spec/armv5te_unknown_linux_gnueabi.rs
index 75e0d4a3db7..8775d8bd58a 100644
--- a/compiler/rustc_target/src/spec/armv5te_unknown_linux_gnueabi.rs
+++ b/compiler/rustc_target/src/spec/armv5te_unknown_linux_gnueabi.rs
@@ -7,7 +7,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/armv5te_unknown_linux_musleabi.rs b/compiler/rustc_target/src/spec/armv5te_unknown_linux_musleabi.rs
index 834b4b38999..da727657cb4 100644
--- a/compiler/rustc_target/src/spec/armv5te_unknown_linux_musleabi.rs
+++ b/compiler/rustc_target/src/spec/armv5te_unknown_linux_musleabi.rs
@@ -10,7 +10,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "linux".to_string(),
         target_env: "musl".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/armv6_unknown_freebsd.rs b/compiler/rustc_target/src/spec/armv6_unknown_freebsd.rs
index 1cd6fae2152..6c03b4840ed 100644
--- a/compiler/rustc_target/src/spec/armv6_unknown_freebsd.rs
+++ b/compiler/rustc_target/src/spec/armv6_unknown_freebsd.rs
@@ -7,7 +7,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "freebsd".to_string(),
         target_env: "gnueabihf".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/armv6_unknown_netbsd_eabihf.rs b/compiler/rustc_target/src/spec/armv6_unknown_netbsd_eabihf.rs
index 9cda9945726..75ce18f8dd9 100644
--- a/compiler/rustc_target/src/spec/armv6_unknown_netbsd_eabihf.rs
+++ b/compiler/rustc_target/src/spec/armv6_unknown_netbsd_eabihf.rs
@@ -8,7 +8,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "netbsd".to_string(),
         target_env: "eabihf".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/armv7_apple_ios.rs b/compiler/rustc_target/src/spec/armv7_apple_ios.rs
index 3df6c2f7c56..3fa2abd3b2a 100644
--- a/compiler/rustc_target/src/spec/armv7_apple_ios.rs
+++ b/compiler/rustc_target/src/spec/armv7_apple_ios.rs
@@ -2,13 +2,12 @@ use super::apple_sdk_base::{opts, Arch};
 use crate::spec::{LinkerFlavor, Target, TargetOptions};
 
 pub fn target() -> Target {
-    let base = opts(Arch::Armv7);
+    let base = opts("ios", Arch::Armv7);
     Target {
         llvm_target: "armv7-apple-ios".to_string(),
         pointer_width: 32,
         data_layout: "e-m:o-p:32:32-Fi8-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32".to_string(),
         arch: "arm".to_string(),
-        target_os: "ios".to_string(),
         target_env: String::new(),
         target_vendor: "apple".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/armv7_linux_androideabi.rs b/compiler/rustc_target/src/spec/armv7_linux_androideabi.rs
index 34ffe21d0cf..ff95bcb6117 100644
--- a/compiler/rustc_target/src/spec/armv7_linux_androideabi.rs
+++ b/compiler/rustc_target/src/spec/armv7_linux_androideabi.rs
@@ -19,7 +19,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "android".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/armv7_unknown_cloudabi_eabihf.rs b/compiler/rustc_target/src/spec/armv7_unknown_cloudabi_eabihf.rs
index e29b9bfee12..e712d7e2690 100644
--- a/compiler/rustc_target/src/spec/armv7_unknown_cloudabi_eabihf.rs
+++ b/compiler/rustc_target/src/spec/armv7_unknown_cloudabi_eabihf.rs
@@ -13,7 +13,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "cloudabi".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/armv7_unknown_freebsd.rs b/compiler/rustc_target/src/spec/armv7_unknown_freebsd.rs
index ca96dccc847..4e26db53f5d 100644
--- a/compiler/rustc_target/src/spec/armv7_unknown_freebsd.rs
+++ b/compiler/rustc_target/src/spec/armv7_unknown_freebsd.rs
@@ -7,7 +7,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "freebsd".to_string(),
         target_env: "gnueabihf".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/armv7_unknown_linux_gnueabi.rs b/compiler/rustc_target/src/spec/armv7_unknown_linux_gnueabi.rs
index b0251a3d9cb..7f31f6183c0 100644
--- a/compiler/rustc_target/src/spec/armv7_unknown_linux_gnueabi.rs
+++ b/compiler/rustc_target/src/spec/armv7_unknown_linux_gnueabi.rs
@@ -10,7 +10,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/armv7_unknown_linux_gnueabihf.rs b/compiler/rustc_target/src/spec/armv7_unknown_linux_gnueabihf.rs
index 97c2fe21d33..edbd923a3d5 100644
--- a/compiler/rustc_target/src/spec/armv7_unknown_linux_gnueabihf.rs
+++ b/compiler/rustc_target/src/spec/armv7_unknown_linux_gnueabihf.rs
@@ -10,7 +10,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/armv7_unknown_linux_musleabi.rs b/compiler/rustc_target/src/spec/armv7_unknown_linux_musleabi.rs
index 095a7c80879..0200ab7240c 100644
--- a/compiler/rustc_target/src/spec/armv7_unknown_linux_musleabi.rs
+++ b/compiler/rustc_target/src/spec/armv7_unknown_linux_musleabi.rs
@@ -15,7 +15,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "linux".to_string(),
         target_env: "musl".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/armv7_unknown_linux_musleabihf.rs b/compiler/rustc_target/src/spec/armv7_unknown_linux_musleabihf.rs
index 414ab7fccf7..5bd32d8aadd 100644
--- a/compiler/rustc_target/src/spec/armv7_unknown_linux_musleabihf.rs
+++ b/compiler/rustc_target/src/spec/armv7_unknown_linux_musleabihf.rs
@@ -12,7 +12,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "linux".to_string(),
         target_env: "musl".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/armv7_unknown_netbsd_eabihf.rs b/compiler/rustc_target/src/spec/armv7_unknown_netbsd_eabihf.rs
index c25a23d8231..5d8eab0c414 100644
--- a/compiler/rustc_target/src/spec/armv7_unknown_netbsd_eabihf.rs
+++ b/compiler/rustc_target/src/spec/armv7_unknown_netbsd_eabihf.rs
@@ -7,7 +7,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "netbsd".to_string(),
         target_env: "eabihf".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/armv7_wrs_vxworks_eabihf.rs b/compiler/rustc_target/src/spec/armv7_wrs_vxworks_eabihf.rs
index e40086dfea4..3615dbce01f 100644
--- a/compiler/rustc_target/src/spec/armv7_wrs_vxworks_eabihf.rs
+++ b/compiler/rustc_target/src/spec/armv7_wrs_vxworks_eabihf.rs
@@ -7,7 +7,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "vxworks".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "wrs".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/armv7a_none_eabi.rs b/compiler/rustc_target/src/spec/armv7a_none_eabi.rs
index c84dbcace72..464d66473cf 100644
--- a/compiler/rustc_target/src/spec/armv7a_none_eabi.rs
+++ b/compiler/rustc_target/src/spec/armv7a_none_eabi.rs
@@ -35,7 +35,6 @@ pub fn target() -> Target {
     Target {
         llvm_target: "armv7a-none-eabi".to_string(),
         pointer_width: 32,
-        target_os: "none".to_string(),
         target_env: String::new(),
         target_vendor: String::new(),
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
diff --git a/compiler/rustc_target/src/spec/armv7a_none_eabihf.rs b/compiler/rustc_target/src/spec/armv7a_none_eabihf.rs
index 432b841ca7d..9f0d91af3e9 100644
--- a/compiler/rustc_target/src/spec/armv7a_none_eabihf.rs
+++ b/compiler/rustc_target/src/spec/armv7a_none_eabihf.rs
@@ -23,7 +23,6 @@ pub fn target() -> Target {
     Target {
         llvm_target: "armv7a-none-eabihf".to_string(),
         pointer_width: 32,
-        target_os: "none".to_string(),
         target_env: String::new(),
         target_vendor: String::new(),
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
diff --git a/compiler/rustc_target/src/spec/armv7r_none_eabi.rs b/compiler/rustc_target/src/spec/armv7r_none_eabi.rs
index 54f105639ff..ad2726e6508 100644
--- a/compiler/rustc_target/src/spec/armv7r_none_eabi.rs
+++ b/compiler/rustc_target/src/spec/armv7r_none_eabi.rs
@@ -9,7 +9,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "none".to_string(),
         target_env: "".to_string(),
         target_vendor: "".to_string(),
         linker_flavor: LinkerFlavor::Lld(LldFlavor::Ld),
diff --git a/compiler/rustc_target/src/spec/armv7r_none_eabihf.rs b/compiler/rustc_target/src/spec/armv7r_none_eabihf.rs
index 7efc0e31da1..bed0126b3d9 100644
--- a/compiler/rustc_target/src/spec/armv7r_none_eabihf.rs
+++ b/compiler/rustc_target/src/spec/armv7r_none_eabihf.rs
@@ -9,7 +9,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "none".to_string(),
         target_env: "".to_string(),
         target_vendor: "".to_string(),
         linker_flavor: LinkerFlavor::Lld(LldFlavor::Ld),
diff --git a/compiler/rustc_target/src/spec/armv7s_apple_ios.rs b/compiler/rustc_target/src/spec/armv7s_apple_ios.rs
index 85892eaf065..fdcb097fb5d 100644
--- a/compiler/rustc_target/src/spec/armv7s_apple_ios.rs
+++ b/compiler/rustc_target/src/spec/armv7s_apple_ios.rs
@@ -2,13 +2,12 @@ use super::apple_sdk_base::{opts, Arch};
 use crate::spec::{LinkerFlavor, Target, TargetOptions};
 
 pub fn target() -> Target {
-    let base = opts(Arch::Armv7s);
+    let base = opts("ios", Arch::Armv7s);
     Target {
         llvm_target: "armv7s-apple-ios".to_string(),
         pointer_width: 32,
         data_layout: "e-m:o-p:32:32-Fi8-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32".to_string(),
         arch: "arm".to_string(),
-        target_os: "ios".to_string(),
         target_env: String::new(),
         target_vendor: "apple".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/avr_gnu_base.rs b/compiler/rustc_target/src/spec/avr_gnu_base.rs
index e2340efadef..65271c2cb77 100644
--- a/compiler/rustc_target/src/spec/avr_gnu_base.rs
+++ b/compiler/rustc_target/src/spec/avr_gnu_base.rs
@@ -10,11 +10,11 @@ pub fn target(target_cpu: String) -> Target {
         llvm_target: "avr-unknown-unknown".to_string(),
         pointer_width: 16,
         linker_flavor: LinkerFlavor::Gcc,
-        target_os: "unknown".to_string(),
         target_env: "".to_string(),
         target_vendor: "unknown".to_string(),
         options: TargetOptions {
             target_c_int_width: "16".to_string(),
+            target_os: "unknown".to_string(),
             cpu: target_cpu.clone(),
             exe_suffix: ".elf".to_string(),
 
diff --git a/compiler/rustc_target/src/spec/cloudabi_base.rs b/compiler/rustc_target/src/spec/cloudabi_base.rs
index 39039435f58..0053adb8552 100644
--- a/compiler/rustc_target/src/spec/cloudabi_base.rs
+++ b/compiler/rustc_target/src/spec/cloudabi_base.rs
@@ -12,6 +12,7 @@ pub fn opts() -> TargetOptions {
     );
 
     TargetOptions {
+        target_os: "cloudabi".to_string(),
         executables: true,
         target_family: None,
         linker_is_gnu: true,
diff --git a/compiler/rustc_target/src/spec/dragonfly_base.rs b/compiler/rustc_target/src/spec/dragonfly_base.rs
index 82dc5f54659..a182e37dd80 100644
--- a/compiler/rustc_target/src/spec/dragonfly_base.rs
+++ b/compiler/rustc_target/src/spec/dragonfly_base.rs
@@ -16,6 +16,7 @@ pub fn opts() -> TargetOptions {
     );
 
     TargetOptions {
+        target_os: "dragonfly".to_string(),
         dynamic_linking: true,
         executables: true,
         target_family: Some("unix".to_string()),
diff --git a/compiler/rustc_target/src/spec/freebsd_base.rs b/compiler/rustc_target/src/spec/freebsd_base.rs
index 051325a8df6..25535117743 100644
--- a/compiler/rustc_target/src/spec/freebsd_base.rs
+++ b/compiler/rustc_target/src/spec/freebsd_base.rs
@@ -16,6 +16,7 @@ pub fn opts() -> TargetOptions {
     );
 
     TargetOptions {
+        target_os: "freebsd".to_string(),
         dynamic_linking: true,
         executables: true,
         target_family: Some("unix".to_string()),
diff --git a/compiler/rustc_target/src/spec/fuchsia_base.rs b/compiler/rustc_target/src/spec/fuchsia_base.rs
index 6f432dc1171..ffd06170d33 100644
--- a/compiler/rustc_target/src/spec/fuchsia_base.rs
+++ b/compiler/rustc_target/src/spec/fuchsia_base.rs
@@ -20,6 +20,7 @@ pub fn opts() -> TargetOptions {
     );
 
     TargetOptions {
+        target_os: "fuchsia".to_string(),
         linker: Some("rust-lld".to_owned()),
         lld_flavor: LldFlavor::Ld,
         dynamic_linking: true,
diff --git a/compiler/rustc_target/src/spec/haiku_base.rs b/compiler/rustc_target/src/spec/haiku_base.rs
index 3d7ae6c302d..3d9dd44e786 100644
--- a/compiler/rustc_target/src/spec/haiku_base.rs
+++ b/compiler/rustc_target/src/spec/haiku_base.rs
@@ -2,6 +2,7 @@ use crate::spec::{RelroLevel, TargetOptions};
 
 pub fn opts() -> TargetOptions {
     TargetOptions {
+        target_os: "haiku".to_string(),
         dynamic_linking: true,
         executables: true,
         has_rpath: false,
diff --git a/compiler/rustc_target/src/spec/hermit_base.rs b/compiler/rustc_target/src/spec/hermit_base.rs
index e063c94cf2c..e2d194afa18 100644
--- a/compiler/rustc_target/src/spec/hermit_base.rs
+++ b/compiler/rustc_target/src/spec/hermit_base.rs
@@ -9,6 +9,7 @@ pub fn opts() -> TargetOptions {
     );
 
     TargetOptions {
+        target_os: "hermit".to_string(),
         linker: Some("rust-lld".to_owned()),
         executables: true,
         has_elf_tls: true,
diff --git a/compiler/rustc_target/src/spec/hermit_kernel_base.rs b/compiler/rustc_target/src/spec/hermit_kernel_base.rs
index 01b9f75637f..e20df9d15aa 100644
--- a/compiler/rustc_target/src/spec/hermit_kernel_base.rs
+++ b/compiler/rustc_target/src/spec/hermit_kernel_base.rs
@@ -9,6 +9,7 @@ pub fn opts() -> TargetOptions {
     );
 
     TargetOptions {
+        target_os: "hermit".to_string(),
         disable_redzone: true,
         linker: Some("rust-lld".to_owned()),
         executables: true,
diff --git a/compiler/rustc_target/src/spec/hexagon_unknown_linux_musl.rs b/compiler/rustc_target/src/spec/hexagon_unknown_linux_musl.rs
index f7df7fcff76..80ef0c747b7 100644
--- a/compiler/rustc_target/src/spec/hexagon_unknown_linux_musl.rs
+++ b/compiler/rustc_target/src/spec/hexagon_unknown_linux_musl.rs
@@ -28,7 +28,6 @@ pub fn target() -> Target {
         )
         .to_string(),
         arch: "hexagon".to_string(),
-        target_os: "linux".to_string(),
         target_env: "musl".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/i386_apple_ios.rs b/compiler/rustc_target/src/spec/i386_apple_ios.rs
index e3e13585af3..15b51be1289 100644
--- a/compiler/rustc_target/src/spec/i386_apple_ios.rs
+++ b/compiler/rustc_target/src/spec/i386_apple_ios.rs
@@ -2,7 +2,7 @@ use super::apple_sdk_base::{opts, Arch};
 use crate::spec::{LinkerFlavor, Target, TargetOptions};
 
 pub fn target() -> Target {
-    let base = opts(Arch::I386);
+    let base = opts("ios", Arch::I386);
     Target {
         llvm_target: "i386-apple-ios".to_string(),
         pointer_width: 32,
@@ -10,7 +10,6 @@ pub fn target() -> Target {
             f64:32:64-f80:128-n8:16:32-S128"
             .to_string(),
         arch: "x86".to_string(),
-        target_os: "ios".to_string(),
         target_env: String::new(),
         target_vendor: "apple".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/i686_apple_darwin.rs b/compiler/rustc_target/src/spec/i686_apple_darwin.rs
index 2f5a3da57ab..dae9654c5c4 100644
--- a/compiler/rustc_target/src/spec/i686_apple_darwin.rs
+++ b/compiler/rustc_target/src/spec/i686_apple_darwin.rs
@@ -1,7 +1,7 @@
 use crate::spec::{LinkerFlavor, Target, TargetOptions};
 
 pub fn target() -> Target {
-    let mut base = super::apple_base::opts();
+    let mut base = super::apple_base::opts("macos");
     base.cpu = "yonah".to_string();
     base.max_atomic_width = Some(64);
     base.pre_link_args.insert(LinkerFlavor::Gcc, vec!["-m32".to_string()]);
@@ -22,7 +22,6 @@ pub fn target() -> Target {
             f64:32:64-f80:128-n8:16:32-S128"
             .to_string(),
         arch: "x86".to_string(),
-        target_os: "macos".to_string(),
         target_env: String::new(),
         target_vendor: "apple".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/i686_linux_android.rs b/compiler/rustc_target/src/spec/i686_linux_android.rs
index f973ec163b1..cb6fbd929f0 100644
--- a/compiler/rustc_target/src/spec/i686_linux_android.rs
+++ b/compiler/rustc_target/src/spec/i686_linux_android.rs
@@ -20,7 +20,6 @@ pub fn target() -> Target {
             f64:32:64-f80:32-n8:16:32-S128"
             .to_string(),
         arch: "x86".to_string(),
-        target_os: "android".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/i686_pc_windows_gnu.rs b/compiler/rustc_target/src/spec/i686_pc_windows_gnu.rs
index 05cd6495448..583938b2ab6 100644
--- a/compiler/rustc_target/src/spec/i686_pc_windows_gnu.rs
+++ b/compiler/rustc_target/src/spec/i686_pc_windows_gnu.rs
@@ -23,7 +23,6 @@ pub fn target() -> Target {
             i64:64-f80:32-n8:16:32-a:0:32-S32"
             .to_string(),
         arch: "x86".to_string(),
-        target_os: "windows".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "pc".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/i686_pc_windows_msvc.rs b/compiler/rustc_target/src/spec/i686_pc_windows_msvc.rs
index a9496dc0636..067081105e4 100644
--- a/compiler/rustc_target/src/spec/i686_pc_windows_msvc.rs
+++ b/compiler/rustc_target/src/spec/i686_pc_windows_msvc.rs
@@ -27,7 +27,6 @@ pub fn target() -> Target {
             i64:64-f80:32-n8:16:32-a:0:32-S32"
             .to_string(),
         arch: "x86".to_string(),
-        target_os: "windows".to_string(),
         target_env: "msvc".to_string(),
         target_vendor: "pc".to_string(),
         linker_flavor: LinkerFlavor::Msvc,
diff --git a/compiler/rustc_target/src/spec/i686_unknown_cloudabi.rs b/compiler/rustc_target/src/spec/i686_unknown_cloudabi.rs
index 1e7cafe785e..cf985332084 100644
--- a/compiler/rustc_target/src/spec/i686_unknown_cloudabi.rs
+++ b/compiler/rustc_target/src/spec/i686_unknown_cloudabi.rs
@@ -15,7 +15,6 @@ pub fn target() -> Target {
             f64:32:64-f80:32-n8:16:32-S128"
             .to_string(),
         arch: "x86".to_string(),
-        target_os: "cloudabi".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/i686_unknown_freebsd.rs b/compiler/rustc_target/src/spec/i686_unknown_freebsd.rs
index 7b03fbae90b..6bc3da0796b 100644
--- a/compiler/rustc_target/src/spec/i686_unknown_freebsd.rs
+++ b/compiler/rustc_target/src/spec/i686_unknown_freebsd.rs
@@ -16,7 +16,6 @@ pub fn target() -> Target {
             f64:32:64-f80:32-n8:16:32-S128"
             .to_string(),
         arch: "x86".to_string(),
-        target_os: "freebsd".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/i686_unknown_haiku.rs b/compiler/rustc_target/src/spec/i686_unknown_haiku.rs
index 5e26a6f5540..77d138a15c9 100644
--- a/compiler/rustc_target/src/spec/i686_unknown_haiku.rs
+++ b/compiler/rustc_target/src/spec/i686_unknown_haiku.rs
@@ -14,7 +14,6 @@ pub fn target() -> Target {
             f64:32:64-f80:32-n8:16:32-S128"
             .to_string(),
         arch: "x86".to_string(),
-        target_os: "haiku".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/i686_unknown_linux_gnu.rs b/compiler/rustc_target/src/spec/i686_unknown_linux_gnu.rs
index 209446e9851..13be539d4c7 100644
--- a/compiler/rustc_target/src/spec/i686_unknown_linux_gnu.rs
+++ b/compiler/rustc_target/src/spec/i686_unknown_linux_gnu.rs
@@ -14,7 +14,6 @@ pub fn target() -> Target {
             f64:32:64-f80:32-n8:16:32-S128"
             .to_string(),
         arch: "x86".to_string(),
-        target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/i686_unknown_linux_musl.rs b/compiler/rustc_target/src/spec/i686_unknown_linux_musl.rs
index 11f23e50233..ab69a567548 100644
--- a/compiler/rustc_target/src/spec/i686_unknown_linux_musl.rs
+++ b/compiler/rustc_target/src/spec/i686_unknown_linux_musl.rs
@@ -29,7 +29,6 @@ pub fn target() -> Target {
             f64:32:64-f80:32-n8:16:32-S128"
             .to_string(),
         arch: "x86".to_string(),
-        target_os: "linux".to_string(),
         target_env: "musl".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/i686_unknown_netbsd.rs b/compiler/rustc_target/src/spec/i686_unknown_netbsd.rs
index 7f94e9d65ae..505c9b55ca1 100644
--- a/compiler/rustc_target/src/spec/i686_unknown_netbsd.rs
+++ b/compiler/rustc_target/src/spec/i686_unknown_netbsd.rs
@@ -14,7 +14,6 @@ pub fn target() -> Target {
             f64:32:64-f80:32-n8:16:32-S128"
             .to_string(),
         arch: "x86".to_string(),
-        target_os: "netbsd".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/i686_unknown_openbsd.rs b/compiler/rustc_target/src/spec/i686_unknown_openbsd.rs
index 8fc72fa3b8f..a70573272ca 100644
--- a/compiler/rustc_target/src/spec/i686_unknown_openbsd.rs
+++ b/compiler/rustc_target/src/spec/i686_unknown_openbsd.rs
@@ -15,7 +15,6 @@ pub fn target() -> Target {
             f64:32:64-f80:32-n8:16:32-S128"
             .to_string(),
         arch: "x86".to_string(),
-        target_os: "openbsd".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/i686_unknown_uefi.rs b/compiler/rustc_target/src/spec/i686_unknown_uefi.rs
index fcc1e77600f..22249ded44b 100644
--- a/compiler/rustc_target/src/spec/i686_unknown_uefi.rs
+++ b/compiler/rustc_target/src/spec/i686_unknown_uefi.rs
@@ -82,7 +82,6 @@ pub fn target() -> Target {
         data_layout: "e-m:x-p:32:32-p270:32:32-p271:32:32-p272:64:64-\
             i64:64-f80:32-n8:16:32-a:0:32-S32"
             .to_string(),
-        target_os: "uefi".to_string(),
         target_env: "".to_string(),
         target_vendor: "unknown".to_string(),
         arch: "x86".to_string(),
diff --git a/compiler/rustc_target/src/spec/i686_uwp_windows_gnu.rs b/compiler/rustc_target/src/spec/i686_uwp_windows_gnu.rs
index 1c8791974e6..199d47c5f24 100644
--- a/compiler/rustc_target/src/spec/i686_uwp_windows_gnu.rs
+++ b/compiler/rustc_target/src/spec/i686_uwp_windows_gnu.rs
@@ -22,7 +22,6 @@ pub fn target() -> Target {
             i64:64-f80:32-n8:16:32-a:0:32-S32"
             .to_string(),
         arch: "x86".to_string(),
-        target_os: "windows".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "uwp".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/i686_uwp_windows_msvc.rs b/compiler/rustc_target/src/spec/i686_uwp_windows_msvc.rs
index 962c69860ca..de2f09dcf9a 100644
--- a/compiler/rustc_target/src/spec/i686_uwp_windows_msvc.rs
+++ b/compiler/rustc_target/src/spec/i686_uwp_windows_msvc.rs
@@ -13,7 +13,6 @@ pub fn target() -> Target {
             i64:64-f80:32-n8:16:32-a:0:32-S32"
             .to_string(),
         arch: "x86".to_string(),
-        target_os: "windows".to_string(),
         target_env: "msvc".to_string(),
         target_vendor: "uwp".to_string(),
         linker_flavor: LinkerFlavor::Msvc,
diff --git a/compiler/rustc_target/src/spec/i686_wrs_vxworks.rs b/compiler/rustc_target/src/spec/i686_wrs_vxworks.rs
index 86c5ca1adbc..dbf65ee1bfb 100644
--- a/compiler/rustc_target/src/spec/i686_wrs_vxworks.rs
+++ b/compiler/rustc_target/src/spec/i686_wrs_vxworks.rs
@@ -14,7 +14,6 @@ pub fn target() -> Target {
             f64:32:64-f80:32-n8:16:32-S128"
             .to_string(),
         arch: "x86".to_string(),
-        target_os: "vxworks".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "wrs".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/illumos_base.rs b/compiler/rustc_target/src/spec/illumos_base.rs
index 214142b88fc..625f7b18b25 100644
--- a/compiler/rustc_target/src/spec/illumos_base.rs
+++ b/compiler/rustc_target/src/spec/illumos_base.rs
@@ -16,6 +16,7 @@ pub fn opts() -> TargetOptions {
     );
 
     TargetOptions {
+        target_os: "illumos".to_string(),
         dynamic_linking: true,
         executables: true,
         has_rpath: true,
diff --git a/compiler/rustc_target/src/spec/l4re_base.rs b/compiler/rustc_target/src/spec/l4re_base.rs
index 5caad10161d..5237b9728b0 100644
--- a/compiler/rustc_target/src/spec/l4re_base.rs
+++ b/compiler/rustc_target/src/spec/l4re_base.rs
@@ -17,6 +17,7 @@ pub fn opts() -> TargetOptions {
     args.insert(LinkerFlavor::Gcc, vec![]);
 
     TargetOptions {
+        target_os: "l4re".to_string(),
         executables: true,
         has_elf_tls: false,
         panic_strategy: PanicStrategy::Abort,
diff --git a/compiler/rustc_target/src/spec/linux_base.rs b/compiler/rustc_target/src/spec/linux_base.rs
index 7ad972b0692..8758e124084 100644
--- a/compiler/rustc_target/src/spec/linux_base.rs
+++ b/compiler/rustc_target/src/spec/linux_base.rs
@@ -19,6 +19,7 @@ pub fn opts() -> TargetOptions {
     );
 
     TargetOptions {
+        target_os: "linux".to_string(),
         dynamic_linking: true,
         executables: true,
         target_family: Some("unix".to_string()),
diff --git a/compiler/rustc_target/src/spec/mips64_unknown_linux_gnuabi64.rs b/compiler/rustc_target/src/spec/mips64_unknown_linux_gnuabi64.rs
index e27d7d073bc..1ca458dd73b 100644
--- a/compiler/rustc_target/src/spec/mips64_unknown_linux_gnuabi64.rs
+++ b/compiler/rustc_target/src/spec/mips64_unknown_linux_gnuabi64.rs
@@ -6,7 +6,6 @@ pub fn target() -> Target {
         pointer_width: 64,
         data_layout: "E-m:e-i8:8:32-i16:16:32-i64:64-n32:64-S128".to_string(),
         arch: "mips64".to_string(),
-        target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/mips64_unknown_linux_muslabi64.rs b/compiler/rustc_target/src/spec/mips64_unknown_linux_muslabi64.rs
index f40f0e587ad..3b715436c17 100644
--- a/compiler/rustc_target/src/spec/mips64_unknown_linux_muslabi64.rs
+++ b/compiler/rustc_target/src/spec/mips64_unknown_linux_muslabi64.rs
@@ -11,7 +11,6 @@ pub fn target() -> Target {
         pointer_width: 64,
         data_layout: "E-m:e-i8:8:32-i16:16:32-i64:64-n32:64-S128".to_string(),
         arch: "mips64".to_string(),
-        target_os: "linux".to_string(),
         target_env: "musl".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/mips64el_unknown_linux_gnuabi64.rs b/compiler/rustc_target/src/spec/mips64el_unknown_linux_gnuabi64.rs
index a54d0e4c307..746f7c04eaa 100644
--- a/compiler/rustc_target/src/spec/mips64el_unknown_linux_gnuabi64.rs
+++ b/compiler/rustc_target/src/spec/mips64el_unknown_linux_gnuabi64.rs
@@ -6,7 +6,6 @@ pub fn target() -> Target {
         pointer_width: 64,
         data_layout: "e-m:e-i8:8:32-i16:16:32-i64:64-n32:64-S128".to_string(),
         arch: "mips64".to_string(),
-        target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/mips64el_unknown_linux_muslabi64.rs b/compiler/rustc_target/src/spec/mips64el_unknown_linux_muslabi64.rs
index b9971c1ebb6..61d1a114591 100644
--- a/compiler/rustc_target/src/spec/mips64el_unknown_linux_muslabi64.rs
+++ b/compiler/rustc_target/src/spec/mips64el_unknown_linux_muslabi64.rs
@@ -11,7 +11,6 @@ pub fn target() -> Target {
         pointer_width: 64,
         data_layout: "e-m:e-i8:8:32-i16:16:32-i64:64-n32:64-S128".to_string(),
         arch: "mips64".to_string(),
-        target_os: "linux".to_string(),
         target_env: "musl".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/mips_unknown_linux_gnu.rs b/compiler/rustc_target/src/spec/mips_unknown_linux_gnu.rs
index 2eaed76e504..0348446faab 100644
--- a/compiler/rustc_target/src/spec/mips_unknown_linux_gnu.rs
+++ b/compiler/rustc_target/src/spec/mips_unknown_linux_gnu.rs
@@ -6,7 +6,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "E-m:m-p:32:32-i8:8:32-i16:16:32-i64:64-n32-S64".to_string(),
         arch: "mips".to_string(),
-        target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/mips_unknown_linux_musl.rs b/compiler/rustc_target/src/spec/mips_unknown_linux_musl.rs
index 47be91a89c7..b323b307041 100644
--- a/compiler/rustc_target/src/spec/mips_unknown_linux_musl.rs
+++ b/compiler/rustc_target/src/spec/mips_unknown_linux_musl.rs
@@ -11,7 +11,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "E-m:m-p:32:32-i8:8:32-i16:16:32-i64:64-n32-S64".to_string(),
         arch: "mips".to_string(),
-        target_os: "linux".to_string(),
         target_env: "musl".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/mips_unknown_linux_uclibc.rs b/compiler/rustc_target/src/spec/mips_unknown_linux_uclibc.rs
index 8f5302a1687..d7988fd0e7c 100644
--- a/compiler/rustc_target/src/spec/mips_unknown_linux_uclibc.rs
+++ b/compiler/rustc_target/src/spec/mips_unknown_linux_uclibc.rs
@@ -6,7 +6,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "E-m:m-p:32:32-i8:8:32-i16:16:32-i64:64-n32-S64".to_string(),
         arch: "mips".to_string(),
-        target_os: "linux".to_string(),
         target_env: "uclibc".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/mipsel_sony_psp.rs b/compiler/rustc_target/src/spec/mipsel_sony_psp.rs
index 05828f738e5..b14a23ac248 100644
--- a/compiler/rustc_target/src/spec/mipsel_sony_psp.rs
+++ b/compiler/rustc_target/src/spec/mipsel_sony_psp.rs
@@ -13,12 +13,12 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:m-p:32:32-i8:8:32-i16:16:32-i64:64-n32-S64".to_string(),
         arch: "mips".to_string(),
-        target_os: "psp".to_string(),
         target_env: "".to_string(),
         target_vendor: "sony".to_string(),
         linker_flavor: LinkerFlavor::Lld(LldFlavor::Ld),
 
         options: TargetOptions {
+            target_os: "psp".to_string(),
             cpu: "mips2".to_string(),
             executables: true,
             linker: Some("rust-lld".to_owned()),
diff --git a/compiler/rustc_target/src/spec/mipsel_unknown_linux_gnu.rs b/compiler/rustc_target/src/spec/mipsel_unknown_linux_gnu.rs
index 81178dd23d7..de593329a38 100644
--- a/compiler/rustc_target/src/spec/mipsel_unknown_linux_gnu.rs
+++ b/compiler/rustc_target/src/spec/mipsel_unknown_linux_gnu.rs
@@ -6,7 +6,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:m-p:32:32-i8:8:32-i16:16:32-i64:64-n32-S64".to_string(),
         arch: "mips".to_string(),
-        target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/mipsel_unknown_linux_musl.rs b/compiler/rustc_target/src/spec/mipsel_unknown_linux_musl.rs
index 68660dfb6e8..20d4bdfb0bb 100644
--- a/compiler/rustc_target/src/spec/mipsel_unknown_linux_musl.rs
+++ b/compiler/rustc_target/src/spec/mipsel_unknown_linux_musl.rs
@@ -11,7 +11,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:m-p:32:32-i8:8:32-i16:16:32-i64:64-n32-S64".to_string(),
         arch: "mips".to_string(),
-        target_os: "linux".to_string(),
         target_env: "musl".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/mipsel_unknown_linux_uclibc.rs b/compiler/rustc_target/src/spec/mipsel_unknown_linux_uclibc.rs
index 80a93ade583..56b66faa5ef 100644
--- a/compiler/rustc_target/src/spec/mipsel_unknown_linux_uclibc.rs
+++ b/compiler/rustc_target/src/spec/mipsel_unknown_linux_uclibc.rs
@@ -6,7 +6,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:m-p:32:32-i8:8:32-i16:16:32-i64:64-n32-S64".to_string(),
         arch: "mips".to_string(),
-        target_os: "linux".to_string(),
         target_env: "uclibc".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/mipsisa32r6_unknown_linux_gnu.rs b/compiler/rustc_target/src/spec/mipsisa32r6_unknown_linux_gnu.rs
index bd6ad56f4de..467470bc8c4 100644
--- a/compiler/rustc_target/src/spec/mipsisa32r6_unknown_linux_gnu.rs
+++ b/compiler/rustc_target/src/spec/mipsisa32r6_unknown_linux_gnu.rs
@@ -6,7 +6,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "E-m:m-p:32:32-i8:8:32-i16:16:32-i64:64-n32-S64".to_string(),
         arch: "mips".to_string(),
-        target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/mipsisa32r6el_unknown_linux_gnu.rs b/compiler/rustc_target/src/spec/mipsisa32r6el_unknown_linux_gnu.rs
index 6ae972af070..a5c052e77f0 100644
--- a/compiler/rustc_target/src/spec/mipsisa32r6el_unknown_linux_gnu.rs
+++ b/compiler/rustc_target/src/spec/mipsisa32r6el_unknown_linux_gnu.rs
@@ -6,7 +6,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:m-p:32:32-i8:8:32-i16:16:32-i64:64-n32-S64".to_string(),
         arch: "mips".to_string(),
-        target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/mipsisa64r6_unknown_linux_gnuabi64.rs b/compiler/rustc_target/src/spec/mipsisa64r6_unknown_linux_gnuabi64.rs
index 278ffff40bc..ae6dbcb14c5 100644
--- a/compiler/rustc_target/src/spec/mipsisa64r6_unknown_linux_gnuabi64.rs
+++ b/compiler/rustc_target/src/spec/mipsisa64r6_unknown_linux_gnuabi64.rs
@@ -6,7 +6,6 @@ pub fn target() -> Target {
         pointer_width: 64,
         data_layout: "E-m:e-i8:8:32-i16:16:32-i64:64-n32:64-S128".to_string(),
         arch: "mips64".to_string(),
-        target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/mipsisa64r6el_unknown_linux_gnuabi64.rs b/compiler/rustc_target/src/spec/mipsisa64r6el_unknown_linux_gnuabi64.rs
index 4d785b309cf..4b2a0a1795d 100644
--- a/compiler/rustc_target/src/spec/mipsisa64r6el_unknown_linux_gnuabi64.rs
+++ b/compiler/rustc_target/src/spec/mipsisa64r6el_unknown_linux_gnuabi64.rs
@@ -6,7 +6,6 @@ pub fn target() -> Target {
         pointer_width: 64,
         data_layout: "e-m:e-i8:8:32-i16:16:32-i64:64-n32:64-S128".to_string(),
         arch: "mips64".to_string(),
-        target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/mod.rs b/compiler/rustc_target/src/spec/mod.rs
index 08e3949c728..b226016b3b2 100644
--- a/compiler/rustc_target/src/spec/mod.rs
+++ b/compiler/rustc_target/src/spec/mod.rs
@@ -667,8 +667,6 @@ pub struct Target {
     pub llvm_target: String,
     /// Number of bits in a pointer. Influences the `target_pointer_width` `cfg` variable.
     pub pointer_width: u32,
-    /// OS name to use for conditional compilation.
-    pub target_os: String,
     /// Environment name to use for conditional compilation.
     pub target_env: String,
     /// Vendor name to use for conditional compilation.
@@ -708,6 +706,8 @@ pub struct TargetOptions {
     pub target_endian: String,
     /// Width of c_int type. Defaults to "32".
     pub target_c_int_width: String,
+    /// OS name to use for conditional compilation. Defaults to "none".
+    pub target_os: String,
 
     /// Linker to invoke
     pub linker: Option<String>,
@@ -989,6 +989,7 @@ impl Default for TargetOptions {
             is_builtin: false,
             target_endian: "little".to_string(),
             target_c_int_width: "32".to_string(),
+            target_os: "none".to_string(),
             linker: option_env!("CFG_DEFAULT_LINKER").map(|s| s.to_string()),
             lld_flavor: LldFlavor::Ld,
             pre_link_args: LinkArgs::new(),
@@ -1164,7 +1165,6 @@ impl Target {
                 .map_err(|_| "target-pointer-width must be an integer".to_string())?,
             data_layout: get_req_field("data-layout")?,
             arch: get_req_field("arch")?,
-            target_os: get_req_field("os")?,
             target_env: get_opt_field("env", ""),
             target_vendor: get_opt_field("vendor", "unknown"),
             linker_flavor: LinkerFlavor::from_str(&*get_req_field("linker-flavor")?)
@@ -1179,6 +1179,12 @@ impl Target {
                     base.options.$key_name = s.to_string();
                 }
             } );
+            ($key_name:ident = $json_name:expr) => ( {
+                let name = $json_name;
+                if let Some(s) = obj.find(&name).and_then(Json::as_string) {
+                    base.options.$key_name = s.to_string();
+                }
+            } );
             ($key_name:ident, bool) => ( {
                 let name = (stringify!($key_name)).replace("_", "-");
                 if let Some(s) = obj.find(&name).and_then(Json::as_boolean) {
@@ -1407,6 +1413,7 @@ impl Target {
         key!(is_builtin, bool);
         key!(target_endian);
         key!(target_c_int_width);
+        key!(target_os = "os");
         key!(linker, optional);
         key!(lld_flavor, LldFlavor)?;
         key!(pre_link_objects, link_objects);
@@ -1636,7 +1643,6 @@ impl ToJson for Target {
         target_val!(llvm_target);
         d.insert("target-pointer-width".to_string(), self.pointer_width.to_string().to_json());
         target_val!(arch);
-        target_val!(target_os, "os");
         target_val!(target_env, "env");
         target_val!(target_vendor, "vendor");
         target_val!(data_layout);
@@ -1644,6 +1650,7 @@ impl ToJson for Target {
 
         target_option_val!(target_endian);
         target_option_val!(target_c_int_width);
+        target_option_val!(target_os, "os");
         target_option_val!(is_builtin);
         target_option_val!(linker);
         target_option_val!(lld_flavor);
diff --git a/compiler/rustc_target/src/spec/msp430_none_elf.rs b/compiler/rustc_target/src/spec/msp430_none_elf.rs
index 9170077dcec..0b85d5e31da 100644
--- a/compiler/rustc_target/src/spec/msp430_none_elf.rs
+++ b/compiler/rustc_target/src/spec/msp430_none_elf.rs
@@ -6,7 +6,6 @@ pub fn target() -> Target {
         pointer_width: 16,
         data_layout: "e-m:e-p:16:16-i32:16-i64:16-f32:16-f64:16-a:8-n8:16-S16".to_string(),
         arch: "msp430".to_string(),
-        target_os: "none".to_string(),
         target_env: String::new(),
         target_vendor: String::new(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/netbsd_base.rs b/compiler/rustc_target/src/spec/netbsd_base.rs
index d7baf81fce3..437b50b6f11 100644
--- a/compiler/rustc_target/src/spec/netbsd_base.rs
+++ b/compiler/rustc_target/src/spec/netbsd_base.rs
@@ -14,6 +14,7 @@ pub fn opts() -> TargetOptions {
     );
 
     TargetOptions {
+        target_os: "netbsd".to_string(),
         dynamic_linking: true,
         executables: true,
         target_family: Some("unix".to_string()),
diff --git a/compiler/rustc_target/src/spec/nvptx64_nvidia_cuda.rs b/compiler/rustc_target/src/spec/nvptx64_nvidia_cuda.rs
index 315138878f7..c9a84352c69 100644
--- a/compiler/rustc_target/src/spec/nvptx64_nvidia_cuda.rs
+++ b/compiler/rustc_target/src/spec/nvptx64_nvidia_cuda.rs
@@ -7,7 +7,6 @@ pub fn target() -> Target {
         data_layout: "e-i64:64-i128:128-v16:16-v32:32-n16:32:64".to_string(),
         llvm_target: "nvptx64-nvidia-cuda".to_string(),
 
-        target_os: "cuda".to_string(),
         target_vendor: "nvidia".to_string(),
         target_env: String::new(),
 
@@ -16,6 +15,7 @@ pub fn target() -> Target {
         pointer_width: 64,
 
         options: TargetOptions {
+            target_os: "cuda".to_string(),
             // The linker can be installed from `crates.io`.
             linker: Some("rust-ptx-linker".to_string()),
 
diff --git a/compiler/rustc_target/src/spec/openbsd_base.rs b/compiler/rustc_target/src/spec/openbsd_base.rs
index 92a382e826b..5e83e79d9ed 100644
--- a/compiler/rustc_target/src/spec/openbsd_base.rs
+++ b/compiler/rustc_target/src/spec/openbsd_base.rs
@@ -16,6 +16,7 @@ pub fn opts() -> TargetOptions {
     );
 
     TargetOptions {
+        target_os: "openbsd".to_string(),
         dynamic_linking: true,
         executables: true,
         target_family: Some("unix".to_string()),
diff --git a/compiler/rustc_target/src/spec/powerpc64_unknown_freebsd.rs b/compiler/rustc_target/src/spec/powerpc64_unknown_freebsd.rs
index 803c079db54..2870d56d64c 100644
--- a/compiler/rustc_target/src/spec/powerpc64_unknown_freebsd.rs
+++ b/compiler/rustc_target/src/spec/powerpc64_unknown_freebsd.rs
@@ -11,7 +11,6 @@ pub fn target() -> Target {
         pointer_width: 64,
         data_layout: "E-m:e-i64:64-n32:64".to_string(),
         arch: "powerpc64".to_string(),
-        target_os: "freebsd".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/powerpc64_unknown_linux_gnu.rs b/compiler/rustc_target/src/spec/powerpc64_unknown_linux_gnu.rs
index cf5a10d1152..6091ecfb825 100644
--- a/compiler/rustc_target/src/spec/powerpc64_unknown_linux_gnu.rs
+++ b/compiler/rustc_target/src/spec/powerpc64_unknown_linux_gnu.rs
@@ -15,7 +15,6 @@ pub fn target() -> Target {
         pointer_width: 64,
         data_layout: "E-m:e-i64:64-n32:64".to_string(),
         arch: "powerpc64".to_string(),
-        target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/powerpc64_unknown_linux_musl.rs b/compiler/rustc_target/src/spec/powerpc64_unknown_linux_musl.rs
index 635a0e78d01..988e84a9fb9 100644
--- a/compiler/rustc_target/src/spec/powerpc64_unknown_linux_musl.rs
+++ b/compiler/rustc_target/src/spec/powerpc64_unknown_linux_musl.rs
@@ -11,7 +11,6 @@ pub fn target() -> Target {
         pointer_width: 64,
         data_layout: "E-m:e-i64:64-n32:64".to_string(),
         arch: "powerpc64".to_string(),
-        target_os: "linux".to_string(),
         target_env: "musl".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/powerpc64_wrs_vxworks.rs b/compiler/rustc_target/src/spec/powerpc64_wrs_vxworks.rs
index fcf9bfdd20d..3a52b55dc65 100644
--- a/compiler/rustc_target/src/spec/powerpc64_wrs_vxworks.rs
+++ b/compiler/rustc_target/src/spec/powerpc64_wrs_vxworks.rs
@@ -11,7 +11,6 @@ pub fn target() -> Target {
         pointer_width: 64,
         data_layout: "E-m:e-i64:64-n32:64".to_string(),
         arch: "powerpc64".to_string(),
-        target_os: "vxworks".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "wrs".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/powerpc64le_unknown_linux_gnu.rs b/compiler/rustc_target/src/spec/powerpc64le_unknown_linux_gnu.rs
index 11fafa1201b..1c472bcac29 100644
--- a/compiler/rustc_target/src/spec/powerpc64le_unknown_linux_gnu.rs
+++ b/compiler/rustc_target/src/spec/powerpc64le_unknown_linux_gnu.rs
@@ -11,7 +11,6 @@ pub fn target() -> Target {
         pointer_width: 64,
         data_layout: "e-m:e-i64:64-n32:64".to_string(),
         arch: "powerpc64".to_string(),
-        target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/powerpc64le_unknown_linux_musl.rs b/compiler/rustc_target/src/spec/powerpc64le_unknown_linux_musl.rs
index 23812b72340..2a8aef91601 100644
--- a/compiler/rustc_target/src/spec/powerpc64le_unknown_linux_musl.rs
+++ b/compiler/rustc_target/src/spec/powerpc64le_unknown_linux_musl.rs
@@ -11,7 +11,6 @@ pub fn target() -> Target {
         pointer_width: 64,
         data_layout: "e-m:e-i64:64-n32:64".to_string(),
         arch: "powerpc64".to_string(),
-        target_os: "linux".to_string(),
         target_env: "musl".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/powerpc_unknown_linux_gnu.rs b/compiler/rustc_target/src/spec/powerpc_unknown_linux_gnu.rs
index 45525b9ba9a..7631b46c120 100644
--- a/compiler/rustc_target/src/spec/powerpc_unknown_linux_gnu.rs
+++ b/compiler/rustc_target/src/spec/powerpc_unknown_linux_gnu.rs
@@ -10,7 +10,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "E-m:e-p:32:32-i64:64-n32".to_string(),
         arch: "powerpc".to_string(),
-        target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/powerpc_unknown_linux_gnuspe.rs b/compiler/rustc_target/src/spec/powerpc_unknown_linux_gnuspe.rs
index 677e9bae83a..cc8c051c5dc 100644
--- a/compiler/rustc_target/src/spec/powerpc_unknown_linux_gnuspe.rs
+++ b/compiler/rustc_target/src/spec/powerpc_unknown_linux_gnuspe.rs
@@ -10,7 +10,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "E-m:e-p:32:32-i64:64-n32".to_string(),
         arch: "powerpc".to_string(),
-        target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/powerpc_unknown_linux_musl.rs b/compiler/rustc_target/src/spec/powerpc_unknown_linux_musl.rs
index 243ab7f666b..efc14a77a16 100644
--- a/compiler/rustc_target/src/spec/powerpc_unknown_linux_musl.rs
+++ b/compiler/rustc_target/src/spec/powerpc_unknown_linux_musl.rs
@@ -10,7 +10,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "E-m:e-p:32:32-i64:64-n32".to_string(),
         arch: "powerpc".to_string(),
-        target_os: "linux".to_string(),
         target_env: "musl".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/powerpc_unknown_netbsd.rs b/compiler/rustc_target/src/spec/powerpc_unknown_netbsd.rs
index ef842375b17..08db795494d 100644
--- a/compiler/rustc_target/src/spec/powerpc_unknown_netbsd.rs
+++ b/compiler/rustc_target/src/spec/powerpc_unknown_netbsd.rs
@@ -10,7 +10,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "E-m:e-p:32:32-i64:64-n32".to_string(),
         arch: "powerpc".to_string(),
-        target_os: "netbsd".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/powerpc_wrs_vxworks.rs b/compiler/rustc_target/src/spec/powerpc_wrs_vxworks.rs
index 3e940377ae5..ffb495bebbd 100644
--- a/compiler/rustc_target/src/spec/powerpc_wrs_vxworks.rs
+++ b/compiler/rustc_target/src/spec/powerpc_wrs_vxworks.rs
@@ -11,7 +11,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "E-m:e-p:32:32-i64:64-n32".to_string(),
         arch: "powerpc".to_string(),
-        target_os: "vxworks".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "wrs".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/powerpc_wrs_vxworks_spe.rs b/compiler/rustc_target/src/spec/powerpc_wrs_vxworks_spe.rs
index 9e019bd05d2..719f50da768 100644
--- a/compiler/rustc_target/src/spec/powerpc_wrs_vxworks_spe.rs
+++ b/compiler/rustc_target/src/spec/powerpc_wrs_vxworks_spe.rs
@@ -11,7 +11,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "E-m:e-p:32:32-i64:64-n32".to_string(),
         arch: "powerpc".to_string(),
-        target_os: "vxworks".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "wrs".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/redox_base.rs b/compiler/rustc_target/src/spec/redox_base.rs
index 18cafe654d1..11616045fa8 100644
--- a/compiler/rustc_target/src/spec/redox_base.rs
+++ b/compiler/rustc_target/src/spec/redox_base.rs
@@ -19,6 +19,7 @@ pub fn opts() -> TargetOptions {
     );
 
     TargetOptions {
+        target_os: "redox".to_string(),
         dynamic_linking: true,
         executables: true,
         target_family: Some("unix".to_string()),
diff --git a/compiler/rustc_target/src/spec/riscv32gc_unknown_linux_gnu.rs b/compiler/rustc_target/src/spec/riscv32gc_unknown_linux_gnu.rs
index 5314b53bd39..39d47f4e053 100644
--- a/compiler/rustc_target/src/spec/riscv32gc_unknown_linux_gnu.rs
+++ b/compiler/rustc_target/src/spec/riscv32gc_unknown_linux_gnu.rs
@@ -7,7 +7,6 @@ pub fn target() -> Target {
         target_env: "gnu".to_string(),
         data_layout: "e-m:e-p:32:32-i64:64-n32-S128".to_string(),
         arch: "riscv32".to_string(),
-        target_os: "linux".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
         options: TargetOptions {
diff --git a/compiler/rustc_target/src/spec/riscv32i_unknown_none_elf.rs b/compiler/rustc_target/src/spec/riscv32i_unknown_none_elf.rs
index e7dc614c88d..963a7f7e221 100644
--- a/compiler/rustc_target/src/spec/riscv32i_unknown_none_elf.rs
+++ b/compiler/rustc_target/src/spec/riscv32i_unknown_none_elf.rs
@@ -6,7 +6,6 @@ pub fn target() -> Target {
         data_layout: "e-m:e-p:32:32-i64:64-n32-S128".to_string(),
         llvm_target: "riscv32".to_string(),
         pointer_width: 32,
-        target_os: "none".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         arch: "riscv32".to_string(),
diff --git a/compiler/rustc_target/src/spec/riscv32imac_unknown_none_elf.rs b/compiler/rustc_target/src/spec/riscv32imac_unknown_none_elf.rs
index d7f6048c9c8..d08c851a3a9 100644
--- a/compiler/rustc_target/src/spec/riscv32imac_unknown_none_elf.rs
+++ b/compiler/rustc_target/src/spec/riscv32imac_unknown_none_elf.rs
@@ -6,7 +6,6 @@ pub fn target() -> Target {
         data_layout: "e-m:e-p:32:32-i64:64-n32-S128".to_string(),
         llvm_target: "riscv32".to_string(),
         pointer_width: 32,
-        target_os: "none".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         arch: "riscv32".to_string(),
diff --git a/compiler/rustc_target/src/spec/riscv32imc_unknown_none_elf.rs b/compiler/rustc_target/src/spec/riscv32imc_unknown_none_elf.rs
index 969a689c73e..2671401d170 100644
--- a/compiler/rustc_target/src/spec/riscv32imc_unknown_none_elf.rs
+++ b/compiler/rustc_target/src/spec/riscv32imc_unknown_none_elf.rs
@@ -6,7 +6,6 @@ pub fn target() -> Target {
         data_layout: "e-m:e-p:32:32-i64:64-n32-S128".to_string(),
         llvm_target: "riscv32".to_string(),
         pointer_width: 32,
-        target_os: "none".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         arch: "riscv32".to_string(),
diff --git a/compiler/rustc_target/src/spec/riscv64gc_unknown_linux_gnu.rs b/compiler/rustc_target/src/spec/riscv64gc_unknown_linux_gnu.rs
index aa8e747ff20..c5502aae218 100644
--- a/compiler/rustc_target/src/spec/riscv64gc_unknown_linux_gnu.rs
+++ b/compiler/rustc_target/src/spec/riscv64gc_unknown_linux_gnu.rs
@@ -7,7 +7,6 @@ pub fn target() -> Target {
         target_env: "gnu".to_string(),
         data_layout: "e-m:e-p:64:64-i64:64-i128:128-n64-S128".to_string(),
         arch: "riscv64".to_string(),
-        target_os: "linux".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
         options: TargetOptions {
diff --git a/compiler/rustc_target/src/spec/riscv64gc_unknown_none_elf.rs b/compiler/rustc_target/src/spec/riscv64gc_unknown_none_elf.rs
index 214541484a5..90830f4077a 100644
--- a/compiler/rustc_target/src/spec/riscv64gc_unknown_none_elf.rs
+++ b/compiler/rustc_target/src/spec/riscv64gc_unknown_none_elf.rs
@@ -6,7 +6,6 @@ pub fn target() -> Target {
         data_layout: "e-m:e-p:64:64-i64:64-i128:128-n64-S128".to_string(),
         llvm_target: "riscv64".to_string(),
         pointer_width: 64,
-        target_os: "none".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         arch: "riscv64".to_string(),
diff --git a/compiler/rustc_target/src/spec/riscv64imac_unknown_none_elf.rs b/compiler/rustc_target/src/spec/riscv64imac_unknown_none_elf.rs
index f805a531cdf..374295d04bf 100644
--- a/compiler/rustc_target/src/spec/riscv64imac_unknown_none_elf.rs
+++ b/compiler/rustc_target/src/spec/riscv64imac_unknown_none_elf.rs
@@ -6,7 +6,6 @@ pub fn target() -> Target {
         data_layout: "e-m:e-p:64:64-i64:64-i128:128-n64-S128".to_string(),
         llvm_target: "riscv64".to_string(),
         pointer_width: 64,
-        target_os: "none".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         arch: "riscv64".to_string(),
diff --git a/compiler/rustc_target/src/spec/s390x_unknown_linux_gnu.rs b/compiler/rustc_target/src/spec/s390x_unknown_linux_gnu.rs
index cf5500eea31..53f34eed32a 100644
--- a/compiler/rustc_target/src/spec/s390x_unknown_linux_gnu.rs
+++ b/compiler/rustc_target/src/spec/s390x_unknown_linux_gnu.rs
@@ -17,7 +17,6 @@ pub fn target() -> Target {
         pointer_width: 64,
         data_layout: "E-m:e-i1:8:16-i8:8:16-i64:64-f128:64-a:8:16-n32:64".to_string(),
         arch: "s390x".to_string(),
-        target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/solaris_base.rs b/compiler/rustc_target/src/spec/solaris_base.rs
index 3d7f0034b8b..0374de20018 100644
--- a/compiler/rustc_target/src/spec/solaris_base.rs
+++ b/compiler/rustc_target/src/spec/solaris_base.rs
@@ -2,6 +2,7 @@ use crate::spec::TargetOptions;
 
 pub fn opts() -> TargetOptions {
     TargetOptions {
+        target_os: "solaris".to_string(),
         dynamic_linking: true,
         executables: true,
         has_rpath: true,
diff --git a/compiler/rustc_target/src/spec/sparc64_unknown_linux_gnu.rs b/compiler/rustc_target/src/spec/sparc64_unknown_linux_gnu.rs
index 911183ad9a6..43f494c2d03 100644
--- a/compiler/rustc_target/src/spec/sparc64_unknown_linux_gnu.rs
+++ b/compiler/rustc_target/src/spec/sparc64_unknown_linux_gnu.rs
@@ -11,7 +11,6 @@ pub fn target() -> Target {
         pointer_width: 64,
         data_layout: "E-m:e-i64:64-n32:64-S128".to_string(),
         arch: "sparc64".to_string(),
-        target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/sparc64_unknown_netbsd.rs b/compiler/rustc_target/src/spec/sparc64_unknown_netbsd.rs
index 161ace037e5..5bba6222dbf 100644
--- a/compiler/rustc_target/src/spec/sparc64_unknown_netbsd.rs
+++ b/compiler/rustc_target/src/spec/sparc64_unknown_netbsd.rs
@@ -11,7 +11,6 @@ pub fn target() -> Target {
         pointer_width: 64,
         data_layout: "E-m:e-i64:64-n32:64-S128".to_string(),
         arch: "sparc64".to_string(),
-        target_os: "netbsd".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/sparc64_unknown_openbsd.rs b/compiler/rustc_target/src/spec/sparc64_unknown_openbsd.rs
index 2ba531e9ef9..dec1f2606ef 100644
--- a/compiler/rustc_target/src/spec/sparc64_unknown_openbsd.rs
+++ b/compiler/rustc_target/src/spec/sparc64_unknown_openbsd.rs
@@ -12,7 +12,6 @@ pub fn target() -> Target {
         pointer_width: 64,
         data_layout: "E-m:e-i64:64-n32:64-S128".to_string(),
         arch: "sparc64".to_string(),
-        target_os: "openbsd".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/sparc_unknown_linux_gnu.rs b/compiler/rustc_target/src/spec/sparc_unknown_linux_gnu.rs
index d523a29eda2..8b669a9f733 100644
--- a/compiler/rustc_target/src/spec/sparc_unknown_linux_gnu.rs
+++ b/compiler/rustc_target/src/spec/sparc_unknown_linux_gnu.rs
@@ -12,7 +12,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "E-m:e-p:32:32-i64:64-f128:64-n32-S64".to_string(),
         arch: "sparc".to_string(),
-        target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/sparcv9_sun_solaris.rs b/compiler/rustc_target/src/spec/sparcv9_sun_solaris.rs
index 27146401532..796b6bf876d 100644
--- a/compiler/rustc_target/src/spec/sparcv9_sun_solaris.rs
+++ b/compiler/rustc_target/src/spec/sparcv9_sun_solaris.rs
@@ -17,7 +17,6 @@ pub fn target() -> Target {
         // differentiation from the sparc64, we could, but that would probably
         // just be confusing.
         arch: "sparc64".to_string(),
-        target_os: "solaris".to_string(),
         target_env: String::new(),
         target_vendor: "sun".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/thumbv4t_none_eabi.rs b/compiler/rustc_target/src/spec/thumbv4t_none_eabi.rs
index c50d7d71ee7..d1238e66f66 100644
--- a/compiler/rustc_target/src/spec/thumbv4t_none_eabi.rs
+++ b/compiler/rustc_target/src/spec/thumbv4t_none_eabi.rs
@@ -14,7 +14,6 @@ pub fn target() -> Target {
     Target {
         llvm_target: "thumbv4t-none-eabi".to_string(),
         pointer_width: 32,
-        target_os: "none".to_string(),
         target_env: "".to_string(),
         target_vendor: "".to_string(),
         arch: "arm".to_string(),
diff --git a/compiler/rustc_target/src/spec/thumbv6m_none_eabi.rs b/compiler/rustc_target/src/spec/thumbv6m_none_eabi.rs
index b21853850d6..f89a4b7e827 100644
--- a/compiler/rustc_target/src/spec/thumbv6m_none_eabi.rs
+++ b/compiler/rustc_target/src/spec/thumbv6m_none_eabi.rs
@@ -8,7 +8,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "none".to_string(),
         target_env: String::new(),
         target_vendor: String::new(),
         linker_flavor: LinkerFlavor::Lld(LldFlavor::Ld),
diff --git a/compiler/rustc_target/src/spec/thumbv7a_pc_windows_msvc.rs b/compiler/rustc_target/src/spec/thumbv7a_pc_windows_msvc.rs
index 642fccb9abb..97b412ed023 100644
--- a/compiler/rustc_target/src/spec/thumbv7a_pc_windows_msvc.rs
+++ b/compiler/rustc_target/src/spec/thumbv7a_pc_windows_msvc.rs
@@ -26,7 +26,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:w-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "windows".to_string(),
         target_env: "msvc".to_string(),
         target_vendor: "pc".to_string(),
         linker_flavor: LinkerFlavor::Msvc,
diff --git a/compiler/rustc_target/src/spec/thumbv7a_uwp_windows_msvc.rs b/compiler/rustc_target/src/spec/thumbv7a_uwp_windows_msvc.rs
index 709c70f2547..cc8036d4fb3 100644
--- a/compiler/rustc_target/src/spec/thumbv7a_uwp_windows_msvc.rs
+++ b/compiler/rustc_target/src/spec/thumbv7a_uwp_windows_msvc.rs
@@ -14,7 +14,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:w-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "windows".to_string(),
         target_env: "msvc".to_string(),
         target_vendor: "uwp".to_string(),
         linker_flavor: LinkerFlavor::Msvc,
diff --git a/compiler/rustc_target/src/spec/thumbv7em_none_eabi.rs b/compiler/rustc_target/src/spec/thumbv7em_none_eabi.rs
index bd833ce1138..4bd0585c2d6 100644
--- a/compiler/rustc_target/src/spec/thumbv7em_none_eabi.rs
+++ b/compiler/rustc_target/src/spec/thumbv7em_none_eabi.rs
@@ -17,7 +17,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "none".to_string(),
         target_env: String::new(),
         target_vendor: String::new(),
         linker_flavor: LinkerFlavor::Lld(LldFlavor::Ld),
diff --git a/compiler/rustc_target/src/spec/thumbv7em_none_eabihf.rs b/compiler/rustc_target/src/spec/thumbv7em_none_eabihf.rs
index b735014b885..013370b3dbd 100644
--- a/compiler/rustc_target/src/spec/thumbv7em_none_eabihf.rs
+++ b/compiler/rustc_target/src/spec/thumbv7em_none_eabihf.rs
@@ -16,7 +16,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "none".to_string(),
         target_env: String::new(),
         target_vendor: String::new(),
         linker_flavor: LinkerFlavor::Lld(LldFlavor::Ld),
diff --git a/compiler/rustc_target/src/spec/thumbv7m_none_eabi.rs b/compiler/rustc_target/src/spec/thumbv7m_none_eabi.rs
index 7bd33589266..69263a85385 100644
--- a/compiler/rustc_target/src/spec/thumbv7m_none_eabi.rs
+++ b/compiler/rustc_target/src/spec/thumbv7m_none_eabi.rs
@@ -8,7 +8,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "none".to_string(),
         target_env: String::new(),
         target_vendor: String::new(),
         linker_flavor: LinkerFlavor::Lld(LldFlavor::Ld),
diff --git a/compiler/rustc_target/src/spec/thumbv7neon_linux_androideabi.rs b/compiler/rustc_target/src/spec/thumbv7neon_linux_androideabi.rs
index f628eff477b..4e26c135496 100644
--- a/compiler/rustc_target/src/spec/thumbv7neon_linux_androideabi.rs
+++ b/compiler/rustc_target/src/spec/thumbv7neon_linux_androideabi.rs
@@ -19,7 +19,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "android".to_string(),
         target_env: "".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/thumbv7neon_unknown_linux_gnueabihf.rs b/compiler/rustc_target/src/spec/thumbv7neon_unknown_linux_gnueabihf.rs
index 735a82c785e..1b472718933 100644
--- a/compiler/rustc_target/src/spec/thumbv7neon_unknown_linux_gnueabihf.rs
+++ b/compiler/rustc_target/src/spec/thumbv7neon_unknown_linux_gnueabihf.rs
@@ -13,7 +13,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/thumbv7neon_unknown_linux_musleabihf.rs b/compiler/rustc_target/src/spec/thumbv7neon_unknown_linux_musleabihf.rs
index ab2e9588df6..ac0e6ad7a23 100644
--- a/compiler/rustc_target/src/spec/thumbv7neon_unknown_linux_musleabihf.rs
+++ b/compiler/rustc_target/src/spec/thumbv7neon_unknown_linux_musleabihf.rs
@@ -16,7 +16,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "linux".to_string(),
         target_env: "musl".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/thumbv8m_base_none_eabi.rs b/compiler/rustc_target/src/spec/thumbv8m_base_none_eabi.rs
index e89f07f6c52..a0b4075a9e5 100644
--- a/compiler/rustc_target/src/spec/thumbv8m_base_none_eabi.rs
+++ b/compiler/rustc_target/src/spec/thumbv8m_base_none_eabi.rs
@@ -8,7 +8,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "none".to_string(),
         target_env: String::new(),
         target_vendor: String::new(),
         linker_flavor: LinkerFlavor::Lld(LldFlavor::Ld),
diff --git a/compiler/rustc_target/src/spec/thumbv8m_main_none_eabi.rs b/compiler/rustc_target/src/spec/thumbv8m_main_none_eabi.rs
index 911d5b087f2..8e033f6a8de 100644
--- a/compiler/rustc_target/src/spec/thumbv8m_main_none_eabi.rs
+++ b/compiler/rustc_target/src/spec/thumbv8m_main_none_eabi.rs
@@ -9,7 +9,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "none".to_string(),
         target_env: String::new(),
         target_vendor: String::new(),
         linker_flavor: LinkerFlavor::Lld(LldFlavor::Ld),
diff --git a/compiler/rustc_target/src/spec/thumbv8m_main_none_eabihf.rs b/compiler/rustc_target/src/spec/thumbv8m_main_none_eabihf.rs
index b02d3e8fc92..ed0fca59b34 100644
--- a/compiler/rustc_target/src/spec/thumbv8m_main_none_eabihf.rs
+++ b/compiler/rustc_target/src/spec/thumbv8m_main_none_eabihf.rs
@@ -9,7 +9,6 @@ pub fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
         arch: "arm".to_string(),
-        target_os: "none".to_string(),
         target_env: String::new(),
         target_vendor: String::new(),
         linker_flavor: LinkerFlavor::Lld(LldFlavor::Ld),
diff --git a/compiler/rustc_target/src/spec/uefi_msvc_base.rs b/compiler/rustc_target/src/spec/uefi_msvc_base.rs
index 3f7c78c8e7d..386fed19e3f 100644
--- a/compiler/rustc_target/src/spec/uefi_msvc_base.rs
+++ b/compiler/rustc_target/src/spec/uefi_msvc_base.rs
@@ -37,6 +37,7 @@ pub fn opts() -> TargetOptions {
         .extend(pre_link_args_msvc);
 
     TargetOptions {
+        target_os: "uefi".to_string(),
         disable_redzone: true,
         exe_suffix: ".efi".to_string(),
         allows_weak_linkage: false,
diff --git a/compiler/rustc_target/src/spec/vxworks_base.rs b/compiler/rustc_target/src/spec/vxworks_base.rs
index 777bb58d7db..56a83194e9e 100644
--- a/compiler/rustc_target/src/spec/vxworks_base.rs
+++ b/compiler/rustc_target/src/spec/vxworks_base.rs
@@ -17,6 +17,7 @@ pub fn opts() -> TargetOptions {
     );
 
     TargetOptions {
+        target_os: "vxworks".to_string(),
         linker: Some("wr-c++".to_string()),
         exe_suffix: ".vxe".to_string(),
         dynamic_linking: true,
diff --git a/compiler/rustc_target/src/spec/wasm32_unknown_emscripten.rs b/compiler/rustc_target/src/spec/wasm32_unknown_emscripten.rs
index 3aaf9f6e0de..f0da2c2986b 100644
--- a/compiler/rustc_target/src/spec/wasm32_unknown_emscripten.rs
+++ b/compiler/rustc_target/src/spec/wasm32_unknown_emscripten.rs
@@ -17,6 +17,7 @@ pub fn target() -> Target {
     );
 
     let opts = TargetOptions {
+        target_os: "emscripten".to_string(),
         // emcc emits two files - a .js file to instantiate the wasm and supply platform
         // functionality, and a .wasm file.
         exe_suffix: ".js".to_string(),
@@ -31,7 +32,6 @@ pub fn target() -> Target {
     Target {
         llvm_target: "wasm32-unknown-emscripten".to_string(),
         pointer_width: 32,
-        target_os: "emscripten".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         data_layout: "e-m:e-p:32:32-i64:64-n32:64-S128".to_string(),
diff --git a/compiler/rustc_target/src/spec/wasm32_unknown_unknown.rs b/compiler/rustc_target/src/spec/wasm32_unknown_unknown.rs
index 70727d7d78a..c8c0d7117c9 100644
--- a/compiler/rustc_target/src/spec/wasm32_unknown_unknown.rs
+++ b/compiler/rustc_target/src/spec/wasm32_unknown_unknown.rs
@@ -15,6 +15,7 @@ use super::{LinkerFlavor, LldFlavor, Target};
 
 pub fn target() -> Target {
     let mut options = wasm32_base::options();
+    options.target_os = "unknown".to_string();
     let clang_args = options.pre_link_args.get_mut(&LinkerFlavor::Gcc).unwrap();
 
     // Make sure clang uses LLD as its linker and is configured appropriately
@@ -33,7 +34,6 @@ pub fn target() -> Target {
     Target {
         llvm_target: "wasm32-unknown-unknown".to_string(),
         pointer_width: 32,
-        target_os: "unknown".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         data_layout: "e-m:e-p:32:32-i64:64-n32:64-S128".to_string(),
diff --git a/compiler/rustc_target/src/spec/wasm32_wasi.rs b/compiler/rustc_target/src/spec/wasm32_wasi.rs
index ae076f27529..0bd6c2a9e19 100644
--- a/compiler/rustc_target/src/spec/wasm32_wasi.rs
+++ b/compiler/rustc_target/src/spec/wasm32_wasi.rs
@@ -78,6 +78,7 @@ use super::{crt_objects, LinkerFlavor, LldFlavor, Target};
 pub fn target() -> Target {
     let mut options = wasm32_base::options();
 
+    options.target_os = "wasi".to_string();
     options
         .pre_link_args
         .entry(LinkerFlavor::Gcc)
@@ -107,7 +108,6 @@ pub fn target() -> Target {
     Target {
         llvm_target: "wasm32-wasi".to_string(),
         pointer_width: 32,
-        target_os: "wasi".to_string(),
         target_env: String::new(),
         target_vendor: String::new(),
         data_layout: "e-m:e-p:32:32-i64:64-n32:64-S128".to_string(),
diff --git a/compiler/rustc_target/src/spec/windows_gnu_base.rs b/compiler/rustc_target/src/spec/windows_gnu_base.rs
index 98e42f6c37c..b06f3ebed3c 100644
--- a/compiler/rustc_target/src/spec/windows_gnu_base.rs
+++ b/compiler/rustc_target/src/spec/windows_gnu_base.rs
@@ -62,6 +62,7 @@ pub fn opts() -> TargetOptions {
     late_link_args_static.insert(LinkerFlavor::Lld(LldFlavor::Ld), static_unwind_libs);
 
     TargetOptions {
+        target_os: "windows".to_string(),
         // FIXME(#13846) this should be enabled for windows
         function_sections: false,
         linker: Some("gcc".to_string()),
diff --git a/compiler/rustc_target/src/spec/windows_msvc_base.rs b/compiler/rustc_target/src/spec/windows_msvc_base.rs
index 77171f8672e..68d21473261 100644
--- a/compiler/rustc_target/src/spec/windows_msvc_base.rs
+++ b/compiler/rustc_target/src/spec/windows_msvc_base.rs
@@ -4,6 +4,7 @@ pub fn opts() -> TargetOptions {
     let base = super::msvc_base::opts();
 
     TargetOptions {
+        target_os: "windows".to_string(),
         dynamic_linking: true,
         dll_prefix: String::new(),
         dll_suffix: ".dll".to_string(),
diff --git a/compiler/rustc_target/src/spec/x86_64_apple_darwin.rs b/compiler/rustc_target/src/spec/x86_64_apple_darwin.rs
index 3a35af3d935..38cfcc0593a 100644
--- a/compiler/rustc_target/src/spec/x86_64_apple_darwin.rs
+++ b/compiler/rustc_target/src/spec/x86_64_apple_darwin.rs
@@ -1,7 +1,7 @@
 use crate::spec::{LinkerFlavor, Target, TargetOptions};
 
 pub fn target() -> Target {
-    let mut base = super::apple_base::opts();
+    let mut base = super::apple_base::opts("macos");
     base.cpu = "core2".to_string();
     base.max_atomic_width = Some(128); // core2 support cmpxchg16b
     base.eliminate_frame_pointer = false;
@@ -24,7 +24,6 @@ pub fn target() -> Target {
         data_layout: "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
             .to_string(),
         arch: arch.to_string(),
-        target_os: "macos".to_string(),
         target_env: String::new(),
         target_vendor: "apple".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/x86_64_apple_ios.rs b/compiler/rustc_target/src/spec/x86_64_apple_ios.rs
index 967c4a35cbe..46e1b383c55 100644
--- a/compiler/rustc_target/src/spec/x86_64_apple_ios.rs
+++ b/compiler/rustc_target/src/spec/x86_64_apple_ios.rs
@@ -2,14 +2,13 @@ use super::apple_sdk_base::{opts, Arch};
 use crate::spec::{LinkerFlavor, Target, TargetOptions};
 
 pub fn target() -> Target {
-    let base = opts(Arch::X86_64);
+    let base = opts("ios", Arch::X86_64);
     Target {
         llvm_target: "x86_64-apple-ios".to_string(),
         pointer_width: 64,
         data_layout: "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
             .to_string(),
         arch: "x86_64".to_string(),
-        target_os: "ios".to_string(),
         target_env: String::new(),
         target_vendor: "apple".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/x86_64_apple_ios_macabi.rs b/compiler/rustc_target/src/spec/x86_64_apple_ios_macabi.rs
index c427b91a18d..e2a6d76ef3a 100644
--- a/compiler/rustc_target/src/spec/x86_64_apple_ios_macabi.rs
+++ b/compiler/rustc_target/src/spec/x86_64_apple_ios_macabi.rs
@@ -2,14 +2,13 @@ use super::apple_sdk_base::{opts, Arch};
 use crate::spec::{LinkerFlavor, Target, TargetOptions};
 
 pub fn target() -> Target {
-    let base = opts(Arch::X86_64_macabi);
+    let base = opts("ios", Arch::X86_64_macabi);
     Target {
         llvm_target: "x86_64-apple-ios13.0-macabi".to_string(),
         pointer_width: 64,
         data_layout: "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
             .to_string(),
         arch: "x86_64".to_string(),
-        target_os: "ios".to_string(),
         target_env: String::new(),
         target_vendor: "apple".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/x86_64_apple_tvos.rs b/compiler/rustc_target/src/spec/x86_64_apple_tvos.rs
index 1124fc4b09a..223aabdef5f 100644
--- a/compiler/rustc_target/src/spec/x86_64_apple_tvos.rs
+++ b/compiler/rustc_target/src/spec/x86_64_apple_tvos.rs
@@ -2,13 +2,12 @@ use super::apple_sdk_base::{opts, Arch};
 use crate::spec::{LinkerFlavor, Target, TargetOptions};
 
 pub fn target() -> Target {
-    let base = opts(Arch::X86_64);
+    let base = opts("tvos", Arch::X86_64);
     Target {
         llvm_target: "x86_64-apple-tvos".to_string(),
         pointer_width: 64,
         data_layout: "e-m:o-i64:64-f80:128-n8:16:32:64-S128".to_string(),
         arch: "x86_64".to_string(),
-        target_os: "tvos".to_string(),
         target_env: String::new(),
         target_vendor: "apple".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/x86_64_fortanix_unknown_sgx.rs b/compiler/rustc_target/src/spec/x86_64_fortanix_unknown_sgx.rs
index db1ac26a0e0..6000f0340da 100644
--- a/compiler/rustc_target/src/spec/x86_64_fortanix_unknown_sgx.rs
+++ b/compiler/rustc_target/src/spec/x86_64_fortanix_unknown_sgx.rs
@@ -55,6 +55,7 @@ pub fn target() -> Target {
         "TEXT_SIZE",
     ];
     let opts = TargetOptions {
+        target_os: "unknown".into(),
         dynamic_linking: false,
         executables: true,
         linker_is_gnu: true,
@@ -77,7 +78,6 @@ pub fn target() -> Target {
     Target {
         llvm_target: "x86_64-elf".into(),
         pointer_width: 64,
-        target_os: "unknown".into(),
         target_env: "sgx".into(),
         target_vendor: "fortanix".into(),
         data_layout: "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
diff --git a/compiler/rustc_target/src/spec/x86_64_fuchsia.rs b/compiler/rustc_target/src/spec/x86_64_fuchsia.rs
index 3a2a032e535..e8f9bc4f7ca 100644
--- a/compiler/rustc_target/src/spec/x86_64_fuchsia.rs
+++ b/compiler/rustc_target/src/spec/x86_64_fuchsia.rs
@@ -12,7 +12,6 @@ pub fn target() -> Target {
         data_layout: "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
             .to_string(),
         arch: "x86_64".to_string(),
-        target_os: "fuchsia".to_string(),
         target_env: String::new(),
         target_vendor: String::new(),
         linker_flavor: LinkerFlavor::Lld(LldFlavor::Ld),
diff --git a/compiler/rustc_target/src/spec/x86_64_linux_android.rs b/compiler/rustc_target/src/spec/x86_64_linux_android.rs
index 2a3aaa932b4..24f4df87f6e 100644
--- a/compiler/rustc_target/src/spec/x86_64_linux_android.rs
+++ b/compiler/rustc_target/src/spec/x86_64_linux_android.rs
@@ -15,7 +15,6 @@ pub fn target() -> Target {
         data_layout: "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
             .to_string(),
         arch: "x86_64".to_string(),
-        target_os: "android".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/x86_64_linux_kernel.rs b/compiler/rustc_target/src/spec/x86_64_linux_kernel.rs
index 1ebe53b891f..19080d9361f 100644
--- a/compiler/rustc_target/src/spec/x86_64_linux_kernel.rs
+++ b/compiler/rustc_target/src/spec/x86_64_linux_kernel.rs
@@ -19,7 +19,6 @@ pub fn target() -> Target {
         pointer_width: 64,
         data_layout: "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
             .to_string(),
-        target_os: "none".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "unknown".to_string(),
         arch: "x86_64".to_string(),
diff --git a/compiler/rustc_target/src/spec/x86_64_pc_windows_gnu.rs b/compiler/rustc_target/src/spec/x86_64_pc_windows_gnu.rs
index 5721d01503b..cef07e3de69 100644
--- a/compiler/rustc_target/src/spec/x86_64_pc_windows_gnu.rs
+++ b/compiler/rustc_target/src/spec/x86_64_pc_windows_gnu.rs
@@ -18,7 +18,6 @@ pub fn target() -> Target {
         data_layout: "e-m:w-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
             .to_string(),
         arch: "x86_64".to_string(),
-        target_os: "windows".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "pc".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/x86_64_pc_windows_msvc.rs b/compiler/rustc_target/src/spec/x86_64_pc_windows_msvc.rs
index 94dbfdafc38..70365cd533b 100644
--- a/compiler/rustc_target/src/spec/x86_64_pc_windows_msvc.rs
+++ b/compiler/rustc_target/src/spec/x86_64_pc_windows_msvc.rs
@@ -12,7 +12,6 @@ pub fn target() -> Target {
         data_layout: "e-m:w-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
             .to_string(),
         arch: "x86_64".to_string(),
-        target_os: "windows".to_string(),
         target_env: "msvc".to_string(),
         target_vendor: "pc".to_string(),
         linker_flavor: LinkerFlavor::Msvc,
diff --git a/compiler/rustc_target/src/spec/x86_64_rumprun_netbsd.rs b/compiler/rustc_target/src/spec/x86_64_rumprun_netbsd.rs
index 1ed9cd0af20..378bd05bc71 100644
--- a/compiler/rustc_target/src/spec/x86_64_rumprun_netbsd.rs
+++ b/compiler/rustc_target/src/spec/x86_64_rumprun_netbsd.rs
@@ -19,7 +19,6 @@ pub fn target() -> Target {
         data_layout: "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
             .to_string(),
         arch: "x86_64".to_string(),
-        target_os: "netbsd".to_string(),
         target_env: String::new(),
         target_vendor: "rumprun".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/x86_64_sun_solaris.rs b/compiler/rustc_target/src/spec/x86_64_sun_solaris.rs
index 879060c6d08..7d020ad509e 100644
--- a/compiler/rustc_target/src/spec/x86_64_sun_solaris.rs
+++ b/compiler/rustc_target/src/spec/x86_64_sun_solaris.rs
@@ -13,7 +13,6 @@ pub fn target() -> Target {
         data_layout: "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
             .to_string(),
         arch: "x86_64".to_string(),
-        target_os: "solaris".to_string(),
         target_env: String::new(),
         target_vendor: "sun".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/x86_64_unknown_cloudabi.rs b/compiler/rustc_target/src/spec/x86_64_unknown_cloudabi.rs
index 87fabb3ee45..cc91c1e035d 100644
--- a/compiler/rustc_target/src/spec/x86_64_unknown_cloudabi.rs
+++ b/compiler/rustc_target/src/spec/x86_64_unknown_cloudabi.rs
@@ -14,7 +14,6 @@ pub fn target() -> Target {
         data_layout: "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
             .to_string(),
         arch: "x86_64".to_string(),
-        target_os: "cloudabi".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/x86_64_unknown_dragonfly.rs b/compiler/rustc_target/src/spec/x86_64_unknown_dragonfly.rs
index b4dfb6a9e0c..451bf187d57 100644
--- a/compiler/rustc_target/src/spec/x86_64_unknown_dragonfly.rs
+++ b/compiler/rustc_target/src/spec/x86_64_unknown_dragonfly.rs
@@ -13,7 +13,6 @@ pub fn target() -> Target {
         data_layout: "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
             .to_string(),
         arch: "x86_64".to_string(),
-        target_os: "dragonfly".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/x86_64_unknown_freebsd.rs b/compiler/rustc_target/src/spec/x86_64_unknown_freebsd.rs
index 884a00f9844..9ecdba13461 100644
--- a/compiler/rustc_target/src/spec/x86_64_unknown_freebsd.rs
+++ b/compiler/rustc_target/src/spec/x86_64_unknown_freebsd.rs
@@ -13,7 +13,6 @@ pub fn target() -> Target {
         data_layout: "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
             .to_string(),
         arch: "x86_64".to_string(),
-        target_os: "freebsd".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/x86_64_unknown_haiku.rs b/compiler/rustc_target/src/spec/x86_64_unknown_haiku.rs
index 18d68596e12..bedc4073f36 100644
--- a/compiler/rustc_target/src/spec/x86_64_unknown_haiku.rs
+++ b/compiler/rustc_target/src/spec/x86_64_unknown_haiku.rs
@@ -15,7 +15,6 @@ pub fn target() -> Target {
         data_layout: "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
             .to_string(),
         arch: "x86_64".to_string(),
-        target_os: "haiku".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/x86_64_unknown_hermit.rs b/compiler/rustc_target/src/spec/x86_64_unknown_hermit.rs
index a00627f343f..be1865f7664 100644
--- a/compiler/rustc_target/src/spec/x86_64_unknown_hermit.rs
+++ b/compiler/rustc_target/src/spec/x86_64_unknown_hermit.rs
@@ -13,7 +13,6 @@ pub fn target() -> Target {
         data_layout: "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
             .to_string(),
         arch: "x86_64".to_string(),
-        target_os: "hermit".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Lld(LldFlavor::Ld),
diff --git a/compiler/rustc_target/src/spec/x86_64_unknown_hermit_kernel.rs b/compiler/rustc_target/src/spec/x86_64_unknown_hermit_kernel.rs
index 08f501e3bb0..9eed950a968 100644
--- a/compiler/rustc_target/src/spec/x86_64_unknown_hermit_kernel.rs
+++ b/compiler/rustc_target/src/spec/x86_64_unknown_hermit_kernel.rs
@@ -15,7 +15,6 @@ pub fn target() -> Target {
         data_layout: "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
             .to_string(),
         arch: "x86_64".to_string(),
-        target_os: "hermit".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Lld(LldFlavor::Ld),
diff --git a/compiler/rustc_target/src/spec/x86_64_unknown_illumos.rs b/compiler/rustc_target/src/spec/x86_64_unknown_illumos.rs
index 51fd05c2712..15e7e965e2d 100644
--- a/compiler/rustc_target/src/spec/x86_64_unknown_illumos.rs
+++ b/compiler/rustc_target/src/spec/x86_64_unknown_illumos.rs
@@ -14,7 +14,6 @@ pub fn target() -> Target {
         data_layout: "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
             .to_string(),
         arch: "x86_64".to_string(),
-        target_os: "illumos".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/x86_64_unknown_l4re_uclibc.rs b/compiler/rustc_target/src/spec/x86_64_unknown_l4re_uclibc.rs
index 956f31973f6..a857c0873ba 100644
--- a/compiler/rustc_target/src/spec/x86_64_unknown_l4re_uclibc.rs
+++ b/compiler/rustc_target/src/spec/x86_64_unknown_l4re_uclibc.rs
@@ -11,7 +11,6 @@ pub fn target() -> Target {
         data_layout: "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
             .to_string(),
         arch: "x86_64".to_string(),
-        target_os: "l4re".to_string(),
         target_env: "uclibc".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Ld,
diff --git a/compiler/rustc_target/src/spec/x86_64_unknown_linux_gnu.rs b/compiler/rustc_target/src/spec/x86_64_unknown_linux_gnu.rs
index e5578ae67a2..bbb63805059 100644
--- a/compiler/rustc_target/src/spec/x86_64_unknown_linux_gnu.rs
+++ b/compiler/rustc_target/src/spec/x86_64_unknown_linux_gnu.rs
@@ -13,7 +13,6 @@ pub fn target() -> Target {
         data_layout: "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
             .to_string(),
         arch: "x86_64".to_string(),
-        target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/x86_64_unknown_linux_gnux32.rs b/compiler/rustc_target/src/spec/x86_64_unknown_linux_gnux32.rs
index 96d172411ec..6a5b3faf98b 100644
--- a/compiler/rustc_target/src/spec/x86_64_unknown_linux_gnux32.rs
+++ b/compiler/rustc_target/src/spec/x86_64_unknown_linux_gnux32.rs
@@ -18,7 +18,6 @@ pub fn target() -> Target {
             i64:64-f80:128-n8:16:32:64-S128"
             .to_string(),
         arch: "x86_64".to_string(),
-        target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/x86_64_unknown_linux_musl.rs b/compiler/rustc_target/src/spec/x86_64_unknown_linux_musl.rs
index 343b6677bb5..e44d28b1641 100644
--- a/compiler/rustc_target/src/spec/x86_64_unknown_linux_musl.rs
+++ b/compiler/rustc_target/src/spec/x86_64_unknown_linux_musl.rs
@@ -14,7 +14,6 @@ pub fn target() -> Target {
         data_layout: "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
             .to_string(),
         arch: "x86_64".to_string(),
-        target_os: "linux".to_string(),
         target_env: "musl".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/x86_64_unknown_netbsd.rs b/compiler/rustc_target/src/spec/x86_64_unknown_netbsd.rs
index 76c741516cb..c5c6570a94d 100644
--- a/compiler/rustc_target/src/spec/x86_64_unknown_netbsd.rs
+++ b/compiler/rustc_target/src/spec/x86_64_unknown_netbsd.rs
@@ -13,7 +13,6 @@ pub fn target() -> Target {
         data_layout: "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
             .to_string(),
         arch: "x86_64".to_string(),
-        target_os: "netbsd".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/x86_64_unknown_openbsd.rs b/compiler/rustc_target/src/spec/x86_64_unknown_openbsd.rs
index 6dc749ef05e..872523c9cea 100644
--- a/compiler/rustc_target/src/spec/x86_64_unknown_openbsd.rs
+++ b/compiler/rustc_target/src/spec/x86_64_unknown_openbsd.rs
@@ -13,7 +13,6 @@ pub fn target() -> Target {
         data_layout: "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
             .to_string(),
         arch: "x86_64".to_string(),
-        target_os: "openbsd".to_string(),
         target_env: String::new(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/x86_64_unknown_redox.rs b/compiler/rustc_target/src/spec/x86_64_unknown_redox.rs
index 824502cb791..bec51a4b9f9 100644
--- a/compiler/rustc_target/src/spec/x86_64_unknown_redox.rs
+++ b/compiler/rustc_target/src/spec/x86_64_unknown_redox.rs
@@ -13,7 +13,6 @@ pub fn target() -> Target {
         data_layout: "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
             .to_string(),
         arch: "x86_64".to_string(),
-        target_os: "redox".to_string(),
         target_env: "relibc".to_string(),
         target_vendor: "unknown".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/x86_64_unknown_uefi.rs b/compiler/rustc_target/src/spec/x86_64_unknown_uefi.rs
index 23e73c423f6..7907247dba3 100644
--- a/compiler/rustc_target/src/spec/x86_64_unknown_uefi.rs
+++ b/compiler/rustc_target/src/spec/x86_64_unknown_uefi.rs
@@ -33,7 +33,6 @@ pub fn target() -> Target {
         pointer_width: 64,
         data_layout: "e-m:w-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
             .to_string(),
-        target_os: "uefi".to_string(),
         target_env: "".to_string(),
         target_vendor: "unknown".to_string(),
         arch: "x86_64".to_string(),
diff --git a/compiler/rustc_target/src/spec/x86_64_uwp_windows_gnu.rs b/compiler/rustc_target/src/spec/x86_64_uwp_windows_gnu.rs
index c156a3a214f..f7c88068eaf 100644
--- a/compiler/rustc_target/src/spec/x86_64_uwp_windows_gnu.rs
+++ b/compiler/rustc_target/src/spec/x86_64_uwp_windows_gnu.rs
@@ -17,7 +17,6 @@ pub fn target() -> Target {
         data_layout: "e-m:w-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
             .to_string(),
         arch: "x86_64".to_string(),
-        target_os: "windows".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "uwp".to_string(),
         linker_flavor: LinkerFlavor::Gcc,
diff --git a/compiler/rustc_target/src/spec/x86_64_uwp_windows_msvc.rs b/compiler/rustc_target/src/spec/x86_64_uwp_windows_msvc.rs
index d5186fb2093..2c74b7a7141 100644
--- a/compiler/rustc_target/src/spec/x86_64_uwp_windows_msvc.rs
+++ b/compiler/rustc_target/src/spec/x86_64_uwp_windows_msvc.rs
@@ -12,7 +12,6 @@ pub fn target() -> Target {
         data_layout: "e-m:w-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
             .to_string(),
         arch: "x86_64".to_string(),
-        target_os: "windows".to_string(),
         target_env: "msvc".to_string(),
         target_vendor: "uwp".to_string(),
         linker_flavor: LinkerFlavor::Msvc,
diff --git a/compiler/rustc_target/src/spec/x86_64_wrs_vxworks.rs b/compiler/rustc_target/src/spec/x86_64_wrs_vxworks.rs
index 4a40ebffcf8..942395bedd0 100644
--- a/compiler/rustc_target/src/spec/x86_64_wrs_vxworks.rs
+++ b/compiler/rustc_target/src/spec/x86_64_wrs_vxworks.rs
@@ -14,7 +14,6 @@ pub fn target() -> Target {
         data_layout: "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
             .to_string(),
         arch: "x86_64".to_string(),
-        target_os: "vxworks".to_string(),
         target_env: "gnu".to_string(),
         target_vendor: "wrs".to_string(),
         linker_flavor: LinkerFlavor::Gcc,