diff --git a/lld/CMakeLists.txt b/lld/CMakeLists.txt
--- a/lld/CMakeLists.txt
+++ b/lld/CMakeLists.txt
@@ -11,6 +11,10 @@
 include(GNUInstallDirs)
 
 if(LLD_BUILT_STANDALONE)
+  set(CMAKE_CXX_STANDARD 14 CACHE STRING "C++ standard to conform to")
+  set(CMAKE_CXX_STANDARD_REQUIRED YES)
+  set(CMAKE_CXX_EXTENSIONS NO)
+
   set(CMAKE_INCLUDE_CURRENT_DIR ON)
 
   # Rely on llvm-config.