diff --git a/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp b/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
--- a/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
+++ b/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
@@ -81,6 +81,7 @@
 
 static cl::opt<int>
     UnswitchThreshold("unswitch-threshold", cl::init(50), cl::Hidden,
+                      cl::ZeroOrMore,
                       cl::desc("The cost threshold for unswitching a loop."));
 
 static cl::opt<bool> EnableUnswitchCostMultiplier(