Index: clang/lib/AST/ASTContext.cpp
===================================================================
--- clang/lib/AST/ASTContext.cpp
+++ clang/lib/AST/ASTContext.cpp
@@ -9566,7 +9566,7 @@
 
   unsigned EltSize = Context.getTypeSize(Info.ElementType);
   unsigned MinElts = Info.EC.getKnownMinValue();
-  return VScale->first * MinElts * EltSize;
+  return VScale->first * static_cast<uint64_t>(MinElts) * EltSize;
 }
 
 bool ASTContext::areCompatibleRVVTypes(QualType FirstType,