Index: include/llvm/Support/Compiler.h
===================================================================
--- include/llvm/Support/Compiler.h
+++ include/llvm/Support/Compiler.h
@@ -519,7 +519,7 @@
 /// reduced default alignment.
 inline void *allocate_buffer(size_t Size, size_t Alignment) {
   return ::operator new(Size
-#if __cpp_aligned_new
+#ifdef __cpp_aligned_new
                         ,
                         std::align_val_t(Alignment)
 #endif
@@ -535,11 +535,11 @@
 /// most likely using the above helper.
 inline void deallocate_buffer(void *Ptr, size_t Size, size_t Alignment) {
   ::operator delete(Ptr
-#if __cpp_sized_deallocation
+#ifdef __cpp_sized_deallocation
                     ,
                     Size
 #endif
-#if __cpp_aligned_new
+#ifdef __cpp_aligned_new
                     ,
                     std::align_val_t(Alignment)
 #endif