diff --git a/llvm/lib/Support/CMakeLists.txt b/llvm/lib/Support/CMakeLists.txt
index a579eaf7d953d..10b6101d73277 100644
--- a/llvm/lib/Support/CMakeLists.txt
+++ b/llvm/lib/Support/CMakeLists.txt
@@ -380,7 +380,7 @@ if(LLVM_WITH_Z3)
     )
 endif()
 
-target_include_directories(LLVMSupport SYSTEM
+target_include_directories(LLVMSupport
   PRIVATE
   ${LLVM_THIRD_PARTY_DIR}/siphash/include
-  )
+)