diff --git a/lib/AST/ItaniumMangle.cpp b/lib/AST/ItaniumMangle.cpp
index 7016ee1..9bce9a0 100644
--- a/lib/AST/ItaniumMangle.cpp
+++ b/lib/AST/ItaniumMangle.cpp
@@ -2230,6 +2230,7 @@
   assert(EltType->isBuiltinType() && "Neon vector element not a BuiltinType");
   unsigned BitSize =
       (T->getNumElements() * getASTContext().getTypeSize(EltType));
+  (void)BitSize; // Silence warning.
 
   assert((BitSize == 64 || BitSize == 128) &&
          "Neon vector type not 64 or 128 bits");