diff --git a/libcxx/utils/ci/run-buildbot b/libcxx/utils/ci/run-buildbot
--- a/libcxx/utils/ci/run-buildbot
+++ b/libcxx/utils/ci/run-buildbot
@@ -12,6 +12,8 @@
 unset LANG
 unset LC_ALL
 unset LC_COLLATE
+export CC=clang-15
+export CXX=clang++-15
 
 PROGNAME="$(basename "${0}")"