diff --git a/lib/Transforms/Utils/LoopUnrollRuntime.cpp b/lib/Transforms/Utils/LoopUnrollRuntime.cpp
index 381d8fc33ea..46570a11a4f 100644
--- a/lib/Transforms/Utils/LoopUnrollRuntime.cpp
+++ b/lib/Transforms/Utils/LoopUnrollRuntime.cpp
@@ -320,7 +320,7 @@ bool llvm::UnrollRuntimeLoopProlog(Loop *L, unsigned Count, LoopInfo *LI,
   // This constraint lets us deal with an overflowing trip count easily; see the
   // comment on ModVal below.  This check is equivalent to `Log2(Count) <
   // BEWidth`.
-  if (static_cast<uint64_t>(Count) > (1ULL << BEWidth))
+  if (BEWidth < 64 && static_cast<uint64_t>(Count) > (1ULL << BEWidth))
     return false;
 
   // If this loop is nested, then the loop unroller changes the code in