diff --git a/src/tools/compiletest/src/runtest.rs b/src/tools/compiletest/src/runtest.rs
index 124a9adcab91a..965b20f5202e0 100644
--- a/src/tools/compiletest/src/runtest.rs
+++ b/src/tools/compiletest/src/runtest.rs
@@ -2782,6 +2782,18 @@ impl<'test> TestCx<'test> {
             cmd.env("RUSTFLAGS", "-Ctarget-feature=-crt-static").env("IS_MUSL_HOST", "1");
         }
 
+        if self.config.bless {
+            cmd.env("RUSTC_BLESS_TEST", "--bless");
+            // Assume this option is active if the environment variable is "defined", with _any_ value.
+            // As an example, a `Makefile` can use this option by:
+            //
+            //   ifdef RUSTC_BLESS_TEST
+            //       cp "$(TMPDIR)"/actual_something.ext expected_something.ext
+            //   else
+            //       $(DIFF) expected_something.ext "$(TMPDIR)"/actual_something.ext
+            //   endif
+        }
+
         if self.config.target.contains("msvc") && self.config.cc != "" {
             // We need to pass a path to `lib.exe`, so assume that `cc` is `cl.exe`
             // and that `lib.exe` lives next to it.