Index: lib/CMakeLists.txt
===================================================================
--- lib/CMakeLists.txt
+++ lib/CMakeLists.txt
@@ -48,7 +48,9 @@
 add_library_flags_if(LIBCXX_ENABLE_STATIC_ABI_LIBRARY "-Wl,-Bdynamic" "-Wl,--no-whole-archive")
 
 if (APPLE AND LLVM_USE_SANITIZER)
-  if ("${LLVM_USE_SANITIZER}" STREQUAL "Address")
+  if ("${LLVM_USE_SANITIZER}" STREQUAL "Address" OR
+      "${LLVM_USE_SANITIZER}" STREQUAL "Address;Undefined" OR
+      "${LLVM_USE_SANITIZER}" STREQUAL "Undefined;Address")
     set(LIBFILE "libclang_rt.asan_osx_dynamic.dylib")
   elseif("${LLVM_USE_SANITIZER}" STREQUAL "Undefined")
     set(LIBFILE "libclang_rt.ubsan_osx_dynamic.dylib")