diff --git a/tools/gccas/gccas.cpp b/tools/gccas/gccas.cpp
index 2791cf4df20..2a45779a4f6 100644
--- a/tools/gccas/gccas.cpp
+++ b/tools/gccas/gccas.cpp
@@ -109,6 +109,7 @@ void AddConfiguredTransformationPasses(PassManager &PM) {
   addPass(PM, createCFGSimplificationPass());    // Merge & remove BBs
   addPass(PM, createReassociatePass());          // Reassociate expressions
   addPass(PM, createLICMPass());                 // Hoist loop invariants
+  addPass(PM, createLoopUnswitchPass());         // Unswitch loops.
   addPass(PM, createInstructionCombiningPass()); // Clean up after LICM/reassoc
   addPass(PM, createIndVarSimplifyPass());       // Canonicalize indvars
   addPass(PM, createLoopUnrollPass());           // Unroll small loops