diff --git a/src/bootstrap/builder.rs b/src/bootstrap/builder.rs
index 22656e5a9da..1e15d539382 100644
--- a/src/bootstrap/builder.rs
+++ b/src/bootstrap/builder.rs
@@ -60,9 +60,6 @@ pub trait Step: 'static + Clone + Debug + PartialEq + Eq + Hash {
     /// Run this rule for all hosts without cross compiling.
     const ONLY_HOSTS: bool = false;
 
-    /// Run this rule for all targets, but only with the native host.
-    const ONLY_BUILD_TARGETS: bool = false;
-
     /// Only run this step with the build triple as host and target.
     const ONLY_BUILD: bool = false;
 
@@ -101,7 +98,6 @@ pub struct RunConfig<'a> {
 struct StepDescription {
     default: bool,
     only_hosts: bool,
-    only_build_targets: bool,
     only_build: bool,
     should_run: fn(ShouldRun) -> ShouldRun,
     make_run: fn(RunConfig),
@@ -138,7 +134,6 @@ impl StepDescription {
         StepDescription {
             default: S::DEFAULT,
             only_hosts: S::ONLY_HOSTS,
-            only_build_targets: S::ONLY_BUILD_TARGETS,
             only_build: S::ONLY_BUILD,
             should_run: S::should_run,
             make_run: S::make_run,
@@ -155,7 +150,7 @@ impl StepDescription {
                 self.name, builder.config.exclude);
         }
         let build = builder.build;
-        let hosts = if self.only_build_targets || self.only_build {
+        let hosts = if self.only_build {
             build.build_triple()
         } else {
             &build.hosts
diff --git a/src/bootstrap/dist.rs b/src/bootstrap/dist.rs
index aa0a7c52246..c3d8c9f8c01 100644
--- a/src/bootstrap/dist.rs
+++ b/src/bootstrap/dist.rs
@@ -70,7 +70,6 @@ pub struct Docs {
 impl Step for Docs {
     type Output = PathBuf;
     const DEFAULT: bool = true;
-    const ONLY_BUILD_TARGETS: bool = true;
 
     fn should_run(run: ShouldRun) -> ShouldRun {
         run.path("src/doc")
@@ -271,7 +270,6 @@ pub struct Mingw {
 impl Step for Mingw {
     type Output = Option<PathBuf>;
     const DEFAULT: bool = true;
-    const ONLY_BUILD_TARGETS: bool = true;
 
     fn should_run(run: ShouldRun) -> ShouldRun {
         run.never()
@@ -331,7 +329,6 @@ impl Step for Rustc {
     type Output = PathBuf;
     const DEFAULT: bool = true;
     const ONLY_HOSTS: bool = true;
-    const ONLY_BUILD_TARGETS: bool = true;
 
     fn should_run(run: ShouldRun) -> ShouldRun {
         run.path("src/librustc")
@@ -561,7 +558,6 @@ pub struct Std {
 impl Step for Std {
     type Output = PathBuf;
     const DEFAULT: bool = true;
-    const ONLY_BUILD_TARGETS: bool = true;
 
     fn should_run(run: ShouldRun) -> ShouldRun {
         run.path("src/libstd")
@@ -569,7 +565,7 @@ impl Step for Std {
 
     fn make_run(run: RunConfig) {
         run.builder.ensure(Std {
-            compiler: run.builder.compiler(run.builder.top_stage, run.host),
+            compiler: run.builder.compiler(run.builder.top_stage, run.builder.build.build),
             target: run.target,
         });
     }
@@ -638,7 +634,6 @@ pub struct Analysis {
 impl Step for Analysis {
     type Output = PathBuf;
     const DEFAULT: bool = true;
-    const ONLY_BUILD_TARGETS: bool = true;
 
     fn should_run(run: ShouldRun) -> ShouldRun {
         let builder = run.builder;
@@ -647,7 +642,7 @@ impl Step for Analysis {
 
     fn make_run(run: RunConfig) {
         run.builder.ensure(Analysis {
-            compiler: run.builder.compiler(run.builder.top_stage, run.host),
+            compiler: run.builder.compiler(run.builder.top_stage, run.builder.build.build),
             target: run.target,
         });
     }
@@ -755,8 +750,6 @@ impl Step for Src {
     type Output = PathBuf;
     const DEFAULT: bool = true;
     const ONLY_HOSTS: bool = true;
-    const ONLY_BUILD_TARGETS: bool = true;
-    const ONLY_BUILD: bool = true;
 
     fn should_run(run: ShouldRun) -> ShouldRun {
         run.path("src")
@@ -851,8 +844,6 @@ impl Step for PlainSourceTarball {
     type Output = PathBuf;
     const DEFAULT: bool = true;
     const ONLY_HOSTS: bool = true;
-    const ONLY_BUILD_TARGETS: bool = true;
-    const ONLY_BUILD: bool = true;
 
     fn should_run(run: ShouldRun) -> ShouldRun {
         let builder = run.builder;
@@ -1007,7 +998,6 @@ pub struct Cargo {
 
 impl Step for Cargo {
     type Output = PathBuf;
-    const ONLY_BUILD_TARGETS: bool = true;
     const ONLY_HOSTS: bool = true;
 
     fn should_run(run: ShouldRun) -> ShouldRun {
@@ -1095,7 +1085,6 @@ pub struct Rls {
 
 impl Step for Rls {
     type Output = Option<PathBuf>;
-    const ONLY_BUILD_TARGETS: bool = true;
     const ONLY_HOSTS: bool = true;
 
     fn should_run(run: ShouldRun) -> ShouldRun {
@@ -1177,7 +1166,6 @@ pub struct Rustfmt {
 
 impl Step for Rustfmt {
     type Output = Option<PathBuf>;
-    const ONLY_BUILD_TARGETS: bool = true;
     const ONLY_HOSTS: bool = true;
 
     fn should_run(run: ShouldRun) -> ShouldRun {
@@ -1263,7 +1251,6 @@ pub struct Extended {
 impl Step for Extended {
     type Output = ();
     const DEFAULT: bool = true;
-    const ONLY_BUILD_TARGETS: bool = true;
     const ONLY_HOSTS: bool = true;
 
     fn should_run(run: ShouldRun) -> ShouldRun {
@@ -1274,7 +1261,7 @@ impl Step for Extended {
     fn make_run(run: RunConfig) {
         run.builder.ensure(Extended {
             stage: run.builder.top_stage,
-            host: run.host,
+            host: run.builder.build.build,
             target: run.target,
         });
     }
@@ -1692,9 +1679,7 @@ pub struct HashSign;
 
 impl Step for HashSign {
     type Output = ();
-    const ONLY_BUILD_TARGETS: bool = true;
     const ONLY_HOSTS: bool = true;
-    const ONLY_BUILD: bool = true;
 
     fn should_run(run: ShouldRun) -> ShouldRun {
         run.path("hash-and-sign")
diff --git a/src/bootstrap/install.rs b/src/bootstrap/install.rs
index 20f7d379a69..fa48902d558 100644
--- a/src/bootstrap/install.rs
+++ b/src/bootstrap/install.rs
@@ -161,7 +161,6 @@ macro_rules! install {
         impl Step for $name {
             type Output = ();
             const DEFAULT: bool = true;
-            const ONLY_BUILD_TARGETS: bool = true;
             const ONLY_HOSTS: bool = $only_hosts;
             $(const $c: bool = true;)*
 
@@ -174,7 +173,7 @@ macro_rules! install {
                 run.builder.ensure($name {
                     stage: run.builder.top_stage,
                     target: run.target,
-                    host: run.host,
+                    host: run.builder.build.build,
                 });
             }