diff --git a/src/bootstrap/lib.rs b/src/bootstrap/lib.rs
index 69b0c4a2756a..5a3785b1ed63 100644
--- a/src/bootstrap/lib.rs
+++ b/src/bootstrap/lib.rs
@@ -482,7 +482,9 @@ fn cargo(&self,
             }
         }
 
-        if self.config.extended && compiler.is_final_stage(self) {
+        if mode == Mode::Libstd &&
+           self.config.extended &&
+           compiler.is_final_stage(self) {
             cargo.env("RUSTC_SAVE_ANALYSIS", "api".to_string());
         }