diff --git a/mk/main.mk b/mk/main.mk
index dedf4ec57ea..cb8af120ca6 100644
--- a/mk/main.mk
+++ b/mk/main.mk
@@ -175,18 +175,6 @@ ifdef CFG_DISABLE_STAGE0_LANDING_PADS
   RUSTFLAGS_STAGE0 += -Z no-landing-pads
 endif
 
-# Enable MIR to "always build" for crates where this works. This is
-# just temporary while MIR is being actively built up -- it's just a
-# poor man's unit testing infrastructure. Anyway we only want this for
-# stage1/stage2.
-define ADD_MIR_FLAG
-RUSTFLAGS1_$(1) += -Z always-build-mir
-RUSTFLAGS2_$(1) += -Z always-build-mir
-endef
-$(foreach crate,$(TARGET_CRATES),$(eval $(call ADD_MIR_FLAG,$(crate))))
-$(foreach crate,$(RUSTC_CRATES),$(eval $(call ADD_MIR_FLAG,$(crate))))
-$(foreach crate,$(HOST_CRATES),$(eval $(call ADD_MIR_FLAG,$(crate))))
-
 # platform-specific auto-configuration
 include $(CFG_SRC_DIR)mk/platform.mk
 
diff --git a/src/librustc/session/config.rs b/src/librustc/session/config.rs
index 0739420ea4d..7e8104d08d6 100644
--- a/src/librustc/session/config.rs
+++ b/src/librustc/session/config.rs
@@ -101,7 +101,6 @@ pub struct Options {
     pub parse_only: bool,
     pub no_trans: bool,
     pub treat_err_as_bug: bool,
-    pub always_build_mir: bool,
     pub no_analysis: bool,
     pub debugging_opts: DebuggingOptions,
     pub prints: Vec<PrintRequest>,
@@ -211,7 +210,6 @@ pub fn basic_options() -> Options {
         parse_only: false,
         no_trans: false,
         treat_err_as_bug: false,
-        always_build_mir: false,
         no_analysis: false,
         debugging_opts: basic_debugging_options(),
         prints: Vec::new(),
@@ -578,8 +576,6 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
           "Run all passes except translation; no output"),
     treat_err_as_bug: bool = (false, parse_bool,
           "Treat all errors that occur as bugs"),
-    always_build_mir: bool = (false, parse_bool,
-          "Always build MIR for all fns, even without a #[rustc_mir] annotation"),
     no_analysis: bool = (false, parse_bool,
           "Parse and expand the source, but run no analysis"),
     extra_plugins: Vec<String> = (Vec::new(), parse_list,
@@ -895,7 +891,6 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
     let parse_only = debugging_opts.parse_only;
     let no_trans = debugging_opts.no_trans;
     let treat_err_as_bug = debugging_opts.treat_err_as_bug;
-    let always_build_mir = debugging_opts.always_build_mir;
     let no_analysis = debugging_opts.no_analysis;
 
     if debugging_opts.debug_llvm {
@@ -1049,7 +1044,6 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
         parse_only: parse_only,
         no_trans: no_trans,
         treat_err_as_bug: treat_err_as_bug,
-        always_build_mir: always_build_mir,
         no_analysis: no_analysis,
         debugging_opts: debugging_opts,
         prints: prints,
diff --git a/src/librustc_mir/dump.rs b/src/librustc_mir/dump.rs
index 5e68e5cc995..ccac2ac61fa 100644
--- a/src/librustc_mir/dump.rs
+++ b/src/librustc_mir/dump.rs
@@ -54,19 +54,14 @@ impl<'a, 'tcx> OuterDump<'a, 'tcx> {
     {
         let mut built_mir = false;
 
+        let mut closure_dump = InnerDump { tcx: self.tcx, attr: None };
         for attr in attributes {
             if attr.check_name("rustc_mir") {
-                let mut closure_dump = InnerDump { tcx: self.tcx, attr: Some(attr) };
-                walk_op(&mut closure_dump);
-                built_mir = true;
+                closure_dump.attr = Some(attr);
             }
         }
 
-        let always_build_mir = true;
-        if !built_mir && always_build_mir {
-            let mut closure_dump = InnerDump { tcx: self.tcx, attr: None };
-            walk_op(&mut closure_dump);
-        }
+        walk_op(&mut closure_dump);
     }
 }