diff --git a/llvm/lib/Support/NativeFormatting.cpp b/llvm/lib/Support/NativeFormatting.cpp
index 0a797046bb684..fa417be95fb7a 100644
--- a/llvm/lib/Support/NativeFormatting.cpp
+++ b/llvm/lib/Support/NativeFormatting.cpp
@@ -258,5 +258,5 @@ size_t llvm::getDefaultPrecision(FloatStyle Style) {
   case FloatStyle::Percent:
     return 2; // Number of decimal places.
   }
-  LLVM_BUILTIN_UNREACHABLE;
+  llvm_unreachable("Unknown FloatStyle enum");
 }