diff --git a/llvm/include/llvm/Support/Compiler.h b/llvm/include/llvm/Support/Compiler.h
index 80ea76240d6cf7..d7001a5c289a82 100644
--- a/llvm/include/llvm/Support/Compiler.h
+++ b/llvm/include/llvm/Support/Compiler.h
@@ -146,7 +146,7 @@
 /// LLVM_NODISCARD - Warn if a type or return value is discarded.
 
 // Use the 'nodiscard' attribute in C++17 or newer mode.
-#if __cplusplus > 201402L && LLVM_HAS_CPP_ATTRIBUTE(nodiscard)
+#if defined(__cplusplus) && __cplusplus > 201402L && LLVM_HAS_CPP_ATTRIBUTE(nodiscard)
 #define LLVM_NODISCARD [[nodiscard]]
 #elif LLVM_HAS_CPP_ATTRIBUTE(clang::warn_unused_result)
 #define LLVM_NODISCARD [[clang::warn_unused_result]]
@@ -268,7 +268,7 @@
 #endif
 
 /// LLVM_FALLTHROUGH - Mark fallthrough cases in switch statements.
-#if __cplusplus > 201402L && LLVM_HAS_CPP_ATTRIBUTE(fallthrough)
+#if defined(__cplusplus) && __cplusplus > 201402L && LLVM_HAS_CPP_ATTRIBUTE(fallthrough)
 #define LLVM_FALLTHROUGH [[fallthrough]]
 #elif LLVM_HAS_CPP_ATTRIBUTE(gnu::fallthrough)
 #define LLVM_FALLTHROUGH [[gnu::fallthrough]]