diff --git a/libcxx/CMakeLists.txt b/libcxx/CMakeLists.txt
--- a/libcxx/CMakeLists.txt
+++ b/libcxx/CMakeLists.txt
@@ -677,6 +677,9 @@
       endif()
     elseif (USE_SANITIZER STREQUAL "Undefined")
       append_flags(SANITIZER_FLAGS "-fsanitize=undefined -fno-sanitize=vptr,function -fno-sanitize-recover=all")
+    elseif (USE_SANITIZER STREQUAL "Address;Undefined" OR
+            USE_SANITIZER STREQUAL "Undefined;Address")
+      append_flags(SANITIZER_FLAGS "-fsanitize=address,undefined -fno-sanitize=vptr,function -fno-sanitize-recover=all")
     elseif (USE_SANITIZER STREQUAL "Thread")
       append_flags(SANITIZER_FLAGS -fsanitize=thread)
     else()