diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyFixFunctionBitcasts.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyFixFunctionBitcasts.cpp
index adf904e..cdbd9ea 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyFixFunctionBitcasts.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyFixFunctionBitcasts.cpp
@@ -148,6 +148,11 @@
     if (!Ty)
       continue;
 
+    // Wasm varargs are not ABI-compatible with non-varargs. Just ignore
+    // such casts for now.
+    if (Ty->isVarArg() || F->isVarArg())
+      continue;
+
     auto Pair = Wrappers.insert(std::make_pair(std::make_pair(F, Ty), nullptr));
     if (Pair.second)
       Pair.first->second = CreateWrapper(F, Ty);