diff --git a/src/bootstrap/bin/rustc.rs b/src/bootstrap/bin/rustc.rs
index 2f674a311fef4..400973780ed2e 100644
--- a/src/bootstrap/bin/rustc.rs
+++ b/src/bootstrap/bin/rustc.rs
@@ -168,6 +168,19 @@ fn main() {
                 cmd.arg("-C").arg(format!("link-args={}", rpath));
             }
         }
+
+        let channel = env::var("RUSTC_CHANNEL").unwrap_or(String::new());
+
+        // Generate MIR for all functions in the Rust libraries
+        // Since users will never build the stdlib themselves, they can't
+        // obtain an stdlib with full MIR. Thus we simply emit MIR always
+        // for the stdlib
+        // Don't do this for stage0 yet, since always_encode_mir isn't part of it yet
+        // Only do this for the nightly and dev channels, we don't want to increase
+        // the size of stable libraries, and noone is able to use MIR on stable anyway
+        if channel != "stable" && channel != "beta" && stage != "0" {
+            cmd.arg("-Zalways-encode-mir");
+        }
     }
 
     // Actually run the compiler!
diff --git a/src/bootstrap/lib.rs b/src/bootstrap/lib.rs
index cd80c4298dc41..a19a0a7978ad2 100644
--- a/src/bootstrap/lib.rs
+++ b/src/bootstrap/lib.rs
@@ -491,6 +491,7 @@ impl Build {
              .env("RUSTC_RPATH", self.config.rust_rpath.to_string())
              .env("RUSTDOC", self.out.join("bootstrap/debug/rustdoc"))
              .env("RUSTDOC_REAL", self.rustdoc(compiler))
+             .env("RUSTC_CHANNEL", &self.config.channel)
              .env("RUSTC_FLAGS", self.rustc_flags(target).join(" "));
 
         // Enable usage of unstable features