diff --git a/libcxx/utils/libcxx/test/params.py b/libcxx/utils/libcxx/test/params.py
index 2c5cb169c0a9a..8ecd1a32799a3 100644
--- a/libcxx/utils/libcxx/test/params.py
+++ b/libcxx/utils/libcxx/test/params.py
@@ -193,7 +193,7 @@ def getSuitableClangTidy(cfg):
         choices=["none", "speed", "size"],
         type=str,
         help="The optimization level to use when compiling the test suite.",
-        default="none",
+        default="speed",
         actions=lambda opt: filter(None, [
             AddCompileFlag(lambda cfg: getSpeedOptimizationFlag(cfg)) if opt == "speed" else None,
             AddCompileFlag(lambda cfg: getSizeOptimizationFlag(cfg)) if opt == "size" else None,