diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index a3aacc7..c942223 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -1816,6 +1816,11 @@
   void *Buffer =
       C.Allocate(totalSizeToAlloc<CastExpr::BasePathSizeTy, CXXBaseSpecifier *>(
           PathSize ? 1 : 0, PathSize));
+  // Per C++ [conv.lval]p3, lvalue-to-rvalue conversions on class and
+  // std::nullptr_t have special semantics not captured by CK_LValueToRValue.
+  assert((Kind != CK_LValueToRValue ||
+          !(T->isNullPtrType() || T->getAsCXXRecordDecl())) &&
+         "invalid type for lvalue-to-rvalue conversion");
   ImplicitCastExpr *E =
     new (Buffer) ImplicitCastExpr(T, Kind, Operand, PathSize, VK);
   if (PathSize)