diff --git a/src/bootstrap/src/utils/tarball.rs b/src/bootstrap/src/utils/tarball.rs
index bfe2f084552e..3f7f6214cf68 100644
--- a/src/bootstrap/src/utils/tarball.rs
+++ b/src/bootstrap/src/utils/tarball.rs
@@ -317,6 +317,12 @@ impl<'a> Tarball<'a> {
             channel::write_commit_hash_file(&self.overlay_dir, &info.sha);
             channel::write_commit_info_file(&self.overlay_dir, info);
         }
+
+        // Add config file if present.
+        if let Some(config) = &self.builder.config.config {
+            self.add_renamed_file(config, &self.overlay_dir, "builder-config");
+        }
+
         for file in self.overlay.legal_and_readme() {
             self.builder.install(&self.builder.src.join(file), &self.overlay_dir, 0o644);
         }