diff --git a/llvm/cmake/modules/CheckAtomic.cmake b/llvm/cmake/modules/CheckAtomic.cmake
--- a/llvm/cmake/modules/CheckAtomic.cmake
+++ b/llvm/cmake/modules/CheckAtomic.cmake
@@ -26,9 +26,10 @@
 #include <atomic>
 #include <cstdint>
 std::atomic<uint64_t> x (0);
+std::atomic<double> y (0);
 int main() {
   uint64_t i = x.load(std::memory_order_relaxed);
-  return 0;
+  return int(y);
 }
 " ${varname})
   set(CMAKE_REQUIRED_FLAGS ${OLD_CMAKE_REQUIRED_FLAGS})