diff --git a/llvm/include/llvm/Demangle/Utility.h b/llvm/include/llvm/Demangle/Utility.h
index d59d74511dd4f..002a1f55467d6 100644
--- a/llvm/include/llvm/Demangle/Utility.h
+++ b/llvm/include/llvm/Demangle/Utility.h
@@ -136,6 +136,8 @@ class OutputBuffer {
 
   OutputBuffer &prepend(std::string_view R) {
     size_t Size = R.size();
+    if (!Size)
+      return *this;
 
     grow(Size);
     std::memmove(Buffer + Size, Buffer, CurrentPosition);