diff --git a/cmake/modules/HandleLLVMOptions.cmake b/cmake/modules/HandleLLVMOptions.cmake
index 76b9c3fb7ed87..405e8ac00daac 100644
--- a/cmake/modules/HandleLLVMOptions.cmake
+++ b/cmake/modules/HandleLLVMOptions.cmake
@@ -507,17 +507,17 @@ if(LLVM_USE_SANITIZER)
       append("-fsanitize=address,undefined -fno-sanitize=vptr,function -fno-sanitize-recover=all"
               CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
     else()
-      message(WARNING "Unsupported value of LLVM_USE_SANITIZER: ${LLVM_USE_SANITIZER}")
+      message(FATAL_ERROR "Unsupported value of LLVM_USE_SANITIZER: ${LLVM_USE_SANITIZER}")
     endif()
   elseif(MSVC)
     if (LLVM_USE_SANITIZER STREQUAL "Address")
       append_common_sanitizer_flags()
       append("-fsanitize=address" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
     else()
-      message(WARNING "This sanitizer not yet supported in the MSVC environment: ${LLVM_USE_SANITIZER}")
+      message(FATAL_ERROR "This sanitizer not yet supported in the MSVC environment: ${LLVM_USE_SANITIZER}")
     endif()
   else()
-    message(WARNING "LLVM_USE_SANITIZER is not supported on this platform.")
+    message(FATAL_ERROR "LLVM_USE_SANITIZER is not supported on this platform.")
   endif()
   if (LLVM_USE_SANITIZE_COVERAGE)
     append("-fsanitize-coverage=edge,indirect-calls,8bit-counters,trace-cmp" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)