diff --git a/.github/workflows/reusable-san.yml b/.github/workflows/reusable-san.yml
index 86a0e65f5258de9..4464e81932447df 100644
--- a/.github/workflows/reusable-san.yml
+++ b/.github/workflows/reusable-san.yml
@@ -67,10 +67,14 @@ jobs:
       env:
         SANITIZER: ${{ inputs.sanitizer }}
         SAN_LOG_OPTION: log_path=${{ github.workspace }}/san_log
+    # gh-157958: -O2 instead of the pydebug default -Og to avoid a clang 21
+    # compile-time blowup on some interpreter files.
+    # (https://github.com/llvm/llvm-project/issues/179695)
     - name: Configure CPython
       run: >-
         ./configure
         --config-cache
+        OPT="-O2 -g"
         ${{
           inputs.sanitizer == 'TSan'
           && '--with-thread-sanitizer'