diff --git a/llvm/CMakeLists.txt b/llvm/CMakeLists.txt
index 47cbea3d0e872..e8d9ec0d6153a 100644
--- a/llvm/CMakeLists.txt
+++ b/llvm/CMakeLists.txt
@@ -76,14 +76,7 @@ endif()
 
 set(CMAKE_CXX_STANDARD ${LLVM_REQUIRED_CXX_STANDARD} CACHE STRING "C++ standard to conform to")
 set(CMAKE_CXX_STANDARD_REQUIRED YES)
-
-if (CYGWIN)
-  # Cygwin is a bit stricter and lack things like 'strdup', 'stricmp', etc in
-  # c++xx mode.
-  set(CMAKE_CXX_EXTENSIONS YES)
-else()
-  set(CMAKE_CXX_EXTENSIONS NO)
-endif()
+set(CMAKE_CXX_EXTENSIONS NO)
 
 if (NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
   message(FATAL_ERROR "