Index: include/llvm/Analysis/TargetTransformInfo.h
===================================================================
--- include/llvm/Analysis/TargetTransformInfo.h
+++ include/llvm/Analysis/TargetTransformInfo.h
@@ -356,6 +356,11 @@
   /// target.
   bool shouldBuildLookupTables() const;
 
+  /// \brief Return true if the switch instruction should be lowered and false
+  /// if the target has a better lowering for this kind of switches that is not
+  /// what the default lower switch pass can do.
+  bool shouldLowerSwitch(const SwitchInst *SI) const;
+
   /// \brief Don't restrict interleaved unrolling to small loops.
   bool enableAggressiveInterleaving(bool LoopHasReductions) const;
 
@@ -614,6 +619,7 @@
   virtual unsigned getJumpBufAlignment() = 0;
   virtual unsigned getJumpBufSize() = 0;
   virtual bool shouldBuildLookupTables() = 0;
+  virtual bool shouldLowerSwitch(const SwitchInst *SI) = 0;
   virtual bool enableAggressiveInterleaving(bool LoopHasReductions) = 0;
   virtual bool enableInterleavedAccessVectorization() = 0;
   virtual PopcntSupportKind getPopcntSupport(unsigned IntTyWidthInBit) = 0;
@@ -766,6 +772,9 @@
   bool shouldBuildLookupTables() override {
     return Impl.shouldBuildLookupTables();
   }
+  bool shouldLowerSwitch(const SwitchInst *SI) override {
+    return Impl.shouldLowerSwitch(SI);
+  }
   bool enableAggressiveInterleaving(bool LoopHasReductions) override {
     return Impl.enableAggressiveInterleaving(LoopHasReductions);
   }
Index: include/llvm/Analysis/TargetTransformInfoImpl.h
===================================================================
--- include/llvm/Analysis/TargetTransformInfoImpl.h
+++ include/llvm/Analysis/TargetTransformInfoImpl.h
@@ -236,6 +236,8 @@
 
   bool shouldBuildLookupTables() { return true; }
 
+  bool shouldLowerSwitch(const SwitchInst *SI) { return true; }
+
   bool enableAggressiveInterleaving(bool LoopHasReductions) { return false; }
 
   bool enableInterleavedAccessVectorization() { return false; }
Index: lib/Analysis/TargetTransformInfo.cpp
===================================================================
--- lib/Analysis/TargetTransformInfo.cpp
+++ lib/Analysis/TargetTransformInfo.cpp
@@ -164,6 +164,10 @@
   return TTIImpl->shouldBuildLookupTables();
 }
 
+bool TargetTransformInfo::shouldLowerSwitch(const SwitchInst *SI) const {
+  return TTIImpl->shouldLowerSwitch(SI);
+}
+
 bool TargetTransformInfo::enableAggressiveInterleaving(bool LoopHasReductions) const {
   return TTIImpl->enableAggressiveInterleaving(LoopHasReductions);
 }
Index: lib/Transforms/Utils/LowerSwitch.cpp
===================================================================
--- lib/Transforms/Utils/LowerSwitch.cpp
+++ lib/Transforms/Utils/LowerSwitch.cpp
@@ -15,6 +15,7 @@
 
 #include "llvm/Transforms/Scalar.h"
 #include "llvm/ADT/STLExtras.h"
+#include "llvm/Analysis/TargetTransformInfo.h"
 #include "llvm/IR/CFG.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/Function.h"
@@ -63,6 +64,7 @@
       // This is a cluster of orthogonal Transforms
       AU.addPreserved<UnifyFunctionExitNodes>();
       AU.addPreservedID(LowerInvokePassID);
+      AU.addRequired<TargetTransformInfoWrapperPass>();
     }
 
     struct CaseRange {
@@ -103,9 +105,11 @@
 }
 
 char LowerSwitch::ID = 0;
-INITIALIZE_PASS(LowerSwitch, "lowerswitch",
-                "Lower SwitchInst's to branches", false, false)
-
+INITIALIZE_PASS_BEGIN(LowerSwitch, "lowerswitch",
+                      "Lower SwitchInst's to branches", false, false)
+INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
+INITIALIZE_PASS_END(LowerSwitch, "lowerswitch",
+                    "Lower SwitchInst's to branches", false, false)
 // Publicly exposed interface to pass...
 char &llvm::LowerSwitchID = LowerSwitch::ID;
 // createLowerSwitchPass - Interface to this file...
@@ -114,6 +118,8 @@
 }
 
 bool LowerSwitch::runOnFunction(Function &F) {
+  const TargetTransformInfo &TTI =
+      getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
   bool Changed = false;
   SmallPtrSet<BasicBlock*, 8> DeleteList;
 
@@ -126,8 +132,10 @@
       continue;
 
     if (SwitchInst *SI = dyn_cast<SwitchInst>(Cur->getTerminator())) {
-      Changed = true;
-      processSwitchInst(SI, DeleteList);
+      if (TTI.shouldLowerSwitch(SI)) {
+        Changed = true;
+        processSwitchInst(SI, DeleteList);
+      }
     }
   }