diff --git a/libcxx/test/CMakeLists.txt b/libcxx/test/CMakeLists.txt
--- a/libcxx/test/CMakeLists.txt
+++ b/libcxx/test/CMakeLists.txt
@@ -46,7 +46,7 @@
 # directory.
 if (NOT LIBCXX_CXX_ABI_LIBRARY_PATH)
   set(LIBCXX_CXX_ABI_LIBRARY_PATH "${LIBCXX_LIBRARY_DIR}" CACHE PATH
-      "The path to libc++abi library.")
+      "The path to libc++abi library." FORCE)
 endif()
 
 set(LIBCXX_TARGET_INFO "libcxx.test.target_info.LocalTI" CACHE STRING