diff --git a/llvm/lib/IR/Function.cpp b/llvm/lib/IR/Function.cpp
--- a/llvm/lib/IR/Function.cpp
+++ b/llvm/lib/IR/Function.cpp
@@ -1495,6 +1495,8 @@
       while (Infos.front().Kind == IITDescriptor::Pointer ||
              Infos.front().Kind == IITDescriptor::Vector)
         Infos = Infos.slice(1);
+      assert(Infos.front().Kind != IITDescriptor::Argument &&
+             "Unsupported polymorphic pointer type with opaque pointer");
       Infos = Infos.slice(1);
       return false;
     }