diff --git a/lib/Serialization/Serialization.cpp b/lib/Serialization/Serialization.cpp
index 537d8b2918a..07cc5efe7be 100644
--- a/lib/Serialization/Serialization.cpp
+++ b/lib/Serialization/Serialization.cpp
@@ -76,8 +76,6 @@
 
 #define DEBUG_TYPE "Serialization"
 
-#pragma clang optimize off
-
 using namespace swift;
 using namespace swift::serialization;
 using namespace llvm::support;