diff --git a/src/tools/compiletest/src/runtest.rs b/src/tools/compiletest/src/runtest.rs
index 2a76113460f..59d94e1fa51 100644
--- a/src/tools/compiletest/src/runtest.rs
+++ b/src/tools/compiletest/src/runtest.rs
@@ -1476,12 +1476,13 @@ impl<'test> TestCx<'test> {
     }
 
     fn compose_and_run_compiler(&self, mut rustc: Command, input: Option<String>) -> ProcRes {
-        if !self.props.aux_builds.is_empty() {
-            create_dir_all(&self.aux_output_dir_name()).unwrap();
-        }
-
         let aux_dir = self.aux_output_dir_name();
 
+        if !self.props.aux_builds.is_empty() {
+            let _ = fs::remove_dir_all(&aux_dir);
+            create_dir_all(&aux_dir).unwrap();
+        }
+
         for rel_ab in &self.props.aux_builds {
             let aux_testpaths = self.compute_aux_test_paths(rel_ab);
             let aux_props =