diff --git a/llvm/include/llvm/ADT/STLExtras.h b/llvm/include/llvm/ADT/STLExtras.h
--- a/llvm/include/llvm/ADT/STLExtras.h
+++ b/llvm/include/llvm/ADT/STLExtras.h
@@ -1363,7 +1363,7 @@
   // but that would be stdlib dependent.
   typedef
       typename std::iterator_traits<Iterator>::difference_type difference_type;
-  for (auto size = last - first; size > 1; ++first, (void)--size) {
+  for (auto size = last - first; size > 1; --size, ++first) {
     difference_type offset = g() % size;
     // Avoid self-assignment due to incorrect assertions in libstdc++
     // containers (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85828).