diff --git a/src/librustc/session/config.rs b/src/librustc/session/config.rs
index 050ccd64712..072761f2754 100644
--- a/src/librustc/session/config.rs
+++ b/src/librustc/session/config.rs
@@ -621,6 +621,7 @@ pub fn default_configuration(sess: &Session) -> ast::CrateConfig {
     let arch = &sess.target.target.arch;
     let wordsz = &sess.target.target.target_pointer_width;
     let os = &sess.target.target.target_os;
+    let env = &sess.target.target.target_env;
 
     let fam = match sess.target.target.options.is_like_windows {
         true  => InternedString::new("windows"),
@@ -634,8 +635,8 @@ pub fn default_configuration(sess: &Session) -> ast::CrateConfig {
          mk(InternedString::new("target_family"), fam),
          mk(InternedString::new("target_arch"), intern(arch)),
          mk(InternedString::new("target_endian"), intern(end)),
-         mk(InternedString::new("target_pointer_width"),
-            intern(wordsz))
+         mk(InternedString::new("target_pointer_width"), intern(wordsz)),
+         mk(InternedString::new("target_env"), intern(env)),
     ];
     if sess.opts.debug_assertions {
         ret.push(attr::mk_word_item(InternedString::new("debug_assertions")));
diff --git a/src/librustc_back/target/aarch64_apple_ios.rs b/src/librustc_back/target/aarch64_apple_ios.rs
index 2ceb34e68b7..dd6bc672a03 100644
--- a/src/librustc_back/target/aarch64_apple_ios.rs
+++ b/src/librustc_back/target/aarch64_apple_ios.rs
@@ -22,6 +22,7 @@ pub fn target() -> Target {
         target_pointer_width: "64".to_string(),
         arch: "aarch64".to_string(),
         target_os: "ios".to_string(),
+        target_env: "".to_string(),
         options: TargetOptions {
             features: "+neon,+fp-armv8,+cyclone".to_string(),
             eliminate_frame_pointer: false,
diff --git a/src/librustc_back/target/aarch64_linux_android.rs b/src/librustc_back/target/aarch64_linux_android.rs
index 64b0e0cfd6b..fcc901fc81f 100644
--- a/src/librustc_back/target/aarch64_linux_android.rs
+++ b/src/librustc_back/target/aarch64_linux_android.rs
@@ -24,6 +24,7 @@ pub fn target() -> Target {
         target_pointer_width: "64".to_string(),
         arch: "aarch64".to_string(),
         target_os: "android".to_string(),
+        target_env: "".to_string(),
         options: base,
     }
 }
diff --git a/src/librustc_back/target/aarch64_unknown_linux_gnu.rs b/src/librustc_back/target/aarch64_unknown_linux_gnu.rs
index a3ef6372f06..18e67d066d0 100644
--- a/src/librustc_back/target/aarch64_unknown_linux_gnu.rs
+++ b/src/librustc_back/target/aarch64_unknown_linux_gnu.rs
@@ -19,6 +19,7 @@ pub fn target() -> Target {
         llvm_target: "aarch64-unknown-linux-gnu".to_string(),
         target_endian: "little".to_string(),
         target_pointer_width: "64".to_string(),
+        target_env: "gnu".to_string(),
         arch: "aarch64".to_string(),
         target_os: "linux".to_string(),
         options: base,
diff --git a/src/librustc_back/target/arm_linux_androideabi.rs b/src/librustc_back/target/arm_linux_androideabi.rs
index fad93441431..57712d18cba 100644
--- a/src/librustc_back/target/arm_linux_androideabi.rs
+++ b/src/librustc_back/target/arm_linux_androideabi.rs
@@ -31,6 +31,7 @@ pub fn target() -> Target {
         target_pointer_width: "32".to_string(),
         arch: "arm".to_string(),
         target_os: "android".to_string(),
+        target_env: "gnu".to_string(),
         options: base,
     }
 }
diff --git a/src/librustc_back/target/arm_unknown_linux_gnueabi.rs b/src/librustc_back/target/arm_unknown_linux_gnueabi.rs
index 32eccaf54b0..30015c4a7e6 100644
--- a/src/librustc_back/target/arm_unknown_linux_gnueabi.rs
+++ b/src/librustc_back/target/arm_unknown_linux_gnueabi.rs
@@ -23,6 +23,7 @@ pub fn target() -> Target {
         target_pointer_width: "32".to_string(),
         arch: "arm".to_string(),
         target_os: "linux".to_string(),
+        target_env: "gnueabi".to_string(),
 
         options: TargetOptions {
             features: "+v6".to_string(),
diff --git a/src/librustc_back/target/arm_unknown_linux_gnueabihf.rs b/src/librustc_back/target/arm_unknown_linux_gnueabihf.rs
index eff3601250f..8f8c7114e6e 100644
--- a/src/librustc_back/target/arm_unknown_linux_gnueabihf.rs
+++ b/src/librustc_back/target/arm_unknown_linux_gnueabihf.rs
@@ -23,6 +23,7 @@ pub fn target() -> Target {
         target_pointer_width: "32".to_string(),
         arch: "arm".to_string(),
         target_os: "linux".to_string(),
+        target_env: "gnueabihf".to_string(),
 
         options: TargetOptions {
             features: "+v6,+vfp2".to_string(),
diff --git a/src/librustc_back/target/armv7_apple_ios.rs b/src/librustc_back/target/armv7_apple_ios.rs
index 41376421886..3b55993659d 100644
--- a/src/librustc_back/target/armv7_apple_ios.rs
+++ b/src/librustc_back/target/armv7_apple_ios.rs
@@ -19,6 +19,7 @@ pub fn target() -> Target {
         target_pointer_width: "32".to_string(),
         arch: "arm".to_string(),
         target_os: "ios".to_string(),
+        target_env: "".to_string(),
         options: TargetOptions {
             features: "+v7,+vfp3,+neon".to_string(),
             .. opts(Arch::Armv7)
diff --git a/src/librustc_back/target/armv7s_apple_ios.rs b/src/librustc_back/target/armv7s_apple_ios.rs
index ef16aefdbd9..5a67e3fe127 100644
--- a/src/librustc_back/target/armv7s_apple_ios.rs
+++ b/src/librustc_back/target/armv7s_apple_ios.rs
@@ -19,6 +19,7 @@ pub fn target() -> Target {
         target_pointer_width: "32".to_string(),
         arch: "arm".to_string(),
         target_os: "ios".to_string(),
+        target_env: "".to_string(),
         options: TargetOptions {
             features: "+v7,+vfp4,+neon".to_string(),
             .. opts(Arch::Armv7s)
diff --git a/src/librustc_back/target/i386_apple_ios.rs b/src/librustc_back/target/i386_apple_ios.rs
index afe63d006cf..a9a073e2a8c 100644
--- a/src/librustc_back/target/i386_apple_ios.rs
+++ b/src/librustc_back/target/i386_apple_ios.rs
@@ -23,6 +23,7 @@ pub fn target() -> Target {
         target_pointer_width: "32".to_string(),
         arch: "x86".to_string(),
         target_os: "ios".to_string(),
+        target_env: "".to_string(),
         options: opts(Arch::I386)
     }
 }
diff --git a/src/librustc_back/target/i686_apple_darwin.rs b/src/librustc_back/target/i686_apple_darwin.rs
index fcea900283d..47b329982d4 100644
--- a/src/librustc_back/target/i686_apple_darwin.rs
+++ b/src/librustc_back/target/i686_apple_darwin.rs
@@ -26,6 +26,7 @@ pub fn target() -> Target {
         target_pointer_width: "32".to_string(),
         arch: "x86".to_string(),
         target_os: "macos".to_string(),
+        target_env: "".to_string(),
         options: base,
     }
 }
diff --git a/src/librustc_back/target/i686_pc_windows_gnu.rs b/src/librustc_back/target/i686_pc_windows_gnu.rs
index 249f2d440e6..9e2aa20085c 100644
--- a/src/librustc_back/target/i686_pc_windows_gnu.rs
+++ b/src/librustc_back/target/i686_pc_windows_gnu.rs
@@ -30,6 +30,7 @@ pub fn target() -> Target {
         target_pointer_width: "32".to_string(),
         arch: "x86".to_string(),
         target_os: "windows".to_string(),
+        target_env: "gnu".to_string(),
         options: options,
     }
 }
diff --git a/src/librustc_back/target/i686_unknown_dragonfly.rs b/src/librustc_back/target/i686_unknown_dragonfly.rs
index 4450d8d6778..ecabe71ad4c 100644
--- a/src/librustc_back/target/i686_unknown_dragonfly.rs
+++ b/src/librustc_back/target/i686_unknown_dragonfly.rs
@@ -22,6 +22,7 @@ pub fn target() -> Target {
         target_pointer_width: "32".to_string(),
         arch: "x86".to_string(),
         target_os: "dragonfly".to_string(),
+        target_env: "".to_string(),
         options: base,
     }
 }
diff --git a/src/librustc_back/target/i686_unknown_linux_gnu.rs b/src/librustc_back/target/i686_unknown_linux_gnu.rs
index f21f6adfb4c..21094ad905e 100644
--- a/src/librustc_back/target/i686_unknown_linux_gnu.rs
+++ b/src/librustc_back/target/i686_unknown_linux_gnu.rs
@@ -22,6 +22,7 @@ pub fn target() -> Target {
         target_pointer_width: "32".to_string(),
         arch: "x86".to_string(),
         target_os: "linux".to_string(),
+        target_env: "gnu".to_string(),
         options: base,
     }
 }
diff --git a/src/librustc_back/target/mips_unknown_linux_gnu.rs b/src/librustc_back/target/mips_unknown_linux_gnu.rs
index 8acc248e234..4662ff1958b 100644
--- a/src/librustc_back/target/mips_unknown_linux_gnu.rs
+++ b/src/librustc_back/target/mips_unknown_linux_gnu.rs
@@ -22,6 +22,7 @@ pub fn target() -> Target {
         target_pointer_width: "32".to_string(),
         arch: "mips".to_string(),
         target_os: "linux".to_string(),
+        target_env: "gnu".to_string(),
         options: super::linux_base::opts()
     }
 }
diff --git a/src/librustc_back/target/mipsel_unknown_linux_gnu.rs b/src/librustc_back/target/mipsel_unknown_linux_gnu.rs
index 604c62eb69f..80e38c5ddea 100644
--- a/src/librustc_back/target/mipsel_unknown_linux_gnu.rs
+++ b/src/librustc_back/target/mipsel_unknown_linux_gnu.rs
@@ -22,6 +22,7 @@ pub fn target() -> Target {
         target_pointer_width: "32".to_string(),
         arch: "mips".to_string(),
         target_os: "linux".to_string(),
+        target_env: "gnu".to_string(),
 
         options: super::linux_base::opts()
     }
diff --git a/src/librustc_back/target/mod.rs b/src/librustc_back/target/mod.rs
index 07528df97f1..cf7499a337d 100644
--- a/src/librustc_back/target/mod.rs
+++ b/src/librustc_back/target/mod.rs
@@ -100,6 +100,8 @@ pub struct Target {
     pub target_pointer_width: String,
     /// OS name to use for conditional compilation.
     pub target_os: String,
+    /// Environment name to use for conditional compilation.
+    pub target_env: String,
     /// Architecture to use for ABI considerations. Valid options: "x86", "x86_64", "arm",
     /// "aarch64", "mips", and "powerpc". "mips" includes "mipsel".
     pub arch: String,
@@ -250,6 +252,8 @@ impl Target {
             target_pointer_width: get_req_field("target-pointer-width"),
             arch: get_req_field("arch"),
             target_os: get_req_field("os"),
+            target_env: obj.find("env").and_then(|s| s.as_string())
+                           .map(|s| s.to_string()).unwrap_or(String::new()),
             options: Default::default(),
         };
 
diff --git a/src/librustc_back/target/powerpc_unknown_linux_gnu.rs b/src/librustc_back/target/powerpc_unknown_linux_gnu.rs
index 5e0b7bcf3ef..3a2b4bd1606 100644
--- a/src/librustc_back/target/powerpc_unknown_linux_gnu.rs
+++ b/src/librustc_back/target/powerpc_unknown_linux_gnu.rs
@@ -21,6 +21,7 @@ pub fn target() -> Target {
         target_pointer_width: "32".to_string(),
         arch: "powerpc".to_string(),
         target_os: "linux".to_string(),
+        target_env: "gnu".to_string(),
         options: base,
     }
 }
diff --git a/src/librustc_back/target/x86_64_apple_darwin.rs b/src/librustc_back/target/x86_64_apple_darwin.rs
index 0b3b2bea62d..89a67da2d8b 100644
--- a/src/librustc_back/target/x86_64_apple_darwin.rs
+++ b/src/librustc_back/target/x86_64_apple_darwin.rs
@@ -25,6 +25,7 @@ pub fn target() -> Target {
         target_pointer_width: "64".to_string(),
         arch: "x86_64".to_string(),
         target_os: "macos".to_string(),
+        target_env: "".to_string(),
         options: base,
     }
 }
diff --git a/src/librustc_back/target/x86_64_apple_ios.rs b/src/librustc_back/target/x86_64_apple_ios.rs
index 9df2ccca500..74491629ed8 100644
--- a/src/librustc_back/target/x86_64_apple_ios.rs
+++ b/src/librustc_back/target/x86_64_apple_ios.rs
@@ -21,6 +21,7 @@ pub fn target() -> Target {
         target_pointer_width: "64".to_string(),
         arch: "x86_64".to_string(),
         target_os: "ios".to_string(),
+        target_env: "".to_string(),
         options: opts(Arch::X86_64)
     }
 }
diff --git a/src/librustc_back/target/x86_64_pc_windows_gnu.rs b/src/librustc_back/target/x86_64_pc_windows_gnu.rs
index 6b3054656fe..bea7d16e9df 100644
--- a/src/librustc_back/target/x86_64_pc_windows_gnu.rs
+++ b/src/librustc_back/target/x86_64_pc_windows_gnu.rs
@@ -27,6 +27,7 @@ pub fn target() -> Target {
         target_pointer_width: "64".to_string(),
         arch: "x86_64".to_string(),
         target_os: "windows".to_string(),
+        target_env: "gnu".to_string(),
         options: base,
     }
 }
diff --git a/src/librustc_back/target/x86_64_unknown_bitrig.rs b/src/librustc_back/target/x86_64_unknown_bitrig.rs
index 7b7877c0c69..201c56b2e15 100644
--- a/src/librustc_back/target/x86_64_unknown_bitrig.rs
+++ b/src/librustc_back/target/x86_64_unknown_bitrig.rs
@@ -23,6 +23,7 @@ pub fn target() -> Target {
         target_pointer_width: "64".to_string(),
         arch: "x86_64".to_string(),
         target_os: "bitrig".to_string(),
+        target_env: "".to_string(),
         options: base,
     }
 }
diff --git a/src/librustc_back/target/x86_64_unknown_dragonfly.rs b/src/librustc_back/target/x86_64_unknown_dragonfly.rs
index 676aaecc2fc..c590f0297b9 100644
--- a/src/librustc_back/target/x86_64_unknown_dragonfly.rs
+++ b/src/librustc_back/target/x86_64_unknown_dragonfly.rs
@@ -24,6 +24,7 @@ pub fn target() -> Target {
         target_pointer_width: "64".to_string(),
         arch: "x86_64".to_string(),
         target_os: "dragonfly".to_string(),
+        target_env: "".to_string(),
         options: base,
     }
 }
diff --git a/src/librustc_back/target/x86_64_unknown_freebsd.rs b/src/librustc_back/target/x86_64_unknown_freebsd.rs
index 3275cb07b5a..0d8ea90a2ab 100644
--- a/src/librustc_back/target/x86_64_unknown_freebsd.rs
+++ b/src/librustc_back/target/x86_64_unknown_freebsd.rs
@@ -24,6 +24,7 @@ pub fn target() -> Target {
         target_pointer_width: "64".to_string(),
         arch: "x86_64".to_string(),
         target_os: "freebsd".to_string(),
+        target_env: "".to_string(),
         options: base,
     }
 }
diff --git a/src/librustc_back/target/x86_64_unknown_linux_gnu.rs b/src/librustc_back/target/x86_64_unknown_linux_gnu.rs
index 49c4ad4aea9..ba945afc564 100644
--- a/src/librustc_back/target/x86_64_unknown_linux_gnu.rs
+++ b/src/librustc_back/target/x86_64_unknown_linux_gnu.rs
@@ -24,6 +24,7 @@ pub fn target() -> Target {
         target_pointer_width: "64".to_string(),
         arch: "x86_64".to_string(),
         target_os: "linux".to_string(),
+        target_env: "gnu".to_string(),
         options: base,
     }
 }
diff --git a/src/librustc_back/target/x86_64_unknown_openbsd.rs b/src/librustc_back/target/x86_64_unknown_openbsd.rs
index d2667dcd1dd..7f64259adf9 100644
--- a/src/librustc_back/target/x86_64_unknown_openbsd.rs
+++ b/src/librustc_back/target/x86_64_unknown_openbsd.rs
@@ -23,6 +23,7 @@ pub fn target() -> Target {
         target_pointer_width: "64".to_string(),
         arch: "x86_64".to_string(),
         target_os: "openbsd".to_string(),
+        target_env: "".to_string(),
         options: base,
     }
 }