diff --git a/llvm/include/llvm/Analysis/TargetTransformInfo.h b/llvm/include/llvm/Analysis/TargetTransformInfo.h
--- a/llvm/include/llvm/Analysis/TargetTransformInfo.h
+++ b/llvm/include/llvm/Analysis/TargetTransformInfo.h
@@ -616,8 +616,8 @@
                              Instruction *I = nullptr) const;
 
   /// Return true if LSR cost of C1 is lower than C1.
-  bool isLSRCostLess(TargetTransformInfo::LSRCost &C1,
-                     TargetTransformInfo::LSRCost &C2) const;
+  bool isLSRCostLess(const TargetTransformInfo::LSRCost &C1,
+                     const TargetTransformInfo::LSRCost &C2) const;
 
   /// Return true if LSR major cost is number of registers. Targets which
   /// implement their own isLSRCostLess and unset number of registers as major
@@ -1557,8 +1557,8 @@
                                      int64_t BaseOffset, bool HasBaseReg,
                                      int64_t Scale, unsigned AddrSpace,
                                      Instruction *I) = 0;
-  virtual bool isLSRCostLess(TargetTransformInfo::LSRCost &C1,
-                             TargetTransformInfo::LSRCost &C2) = 0;
+  virtual bool isLSRCostLess(const TargetTransformInfo::LSRCost &C1,
+                             const TargetTransformInfo::LSRCost &C2) = 0;
   virtual bool isNumRegsMajorCostOfLSR() = 0;
   virtual bool isProfitableLSRChainElement(Instruction *I) = 0;
   virtual bool canMacroFuseCmp() = 0;
@@ -1949,8 +1949,8 @@
     return Impl.isLegalAddressingMode(Ty, BaseGV, BaseOffset, HasBaseReg, Scale,
                                       AddrSpace, I);
   }
-  bool isLSRCostLess(TargetTransformInfo::LSRCost &C1,
-                     TargetTransformInfo::LSRCost &C2) override {
+  bool isLSRCostLess(const TargetTransformInfo::LSRCost &C1,
+                     const TargetTransformInfo::LSRCost &C2) override {
     return Impl.isLSRCostLess(C1, C2);
   }
   bool isNumRegsMajorCostOfLSR() override {
diff --git a/llvm/include/llvm/Analysis/TargetTransformInfoImpl.h b/llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
--- a/llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
+++ b/llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
@@ -210,7 +210,7 @@
     return !BaseGV && BaseOffset == 0 && (Scale == 0 || Scale == 1);
   }
 
-  bool isLSRCostLess(TTI::LSRCost &C1, TTI::LSRCost &C2) const {
+  bool isLSRCostLess(const TTI::LSRCost &C1, const TTI::LSRCost &C2) const {
     return std::tie(C1.NumRegs, C1.AddRecCost, C1.NumIVMuls, C1.NumBaseAdds,
                     C1.ScaleCost, C1.ImmCost, C1.SetupCost) <
            std::tie(C2.NumRegs, C2.AddRecCost, C2.NumIVMuls, C2.NumBaseAdds,
diff --git a/llvm/lib/Analysis/TargetTransformInfo.cpp b/llvm/lib/Analysis/TargetTransformInfo.cpp
--- a/llvm/lib/Analysis/TargetTransformInfo.cpp
+++ b/llvm/lib/Analysis/TargetTransformInfo.cpp
@@ -348,7 +348,8 @@
                                         Scale, AddrSpace, I);
 }
 
-bool TargetTransformInfo::isLSRCostLess(LSRCost &C1, LSRCost &C2) const {
+bool TargetTransformInfo::isLSRCostLess(const LSRCost &C1,
+                                        const LSRCost &C2) const {
   return TTIImpl->isLSRCostLess(C1, C2);
 }
 
diff --git a/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.h b/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.h
--- a/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.h
+++ b/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.h
@@ -76,8 +76,8 @@
                                OptimizationRemarkEmitter *ORE);
   void getPeelingPreferences(Loop *L, ScalarEvolution &SE,
                              TTI::PeelingPreferences &PP);
-  bool isLSRCostLess(TargetTransformInfo::LSRCost &C1,
-                     TargetTransformInfo::LSRCost &C2);
+  bool isLSRCostLess(const TargetTransformInfo::LSRCost &C1,
+                     const TargetTransformInfo::LSRCost &C2);
   bool isNumRegsMajorCostOfLSR();
   bool shouldBuildRelLookupTables() const;
   /// @}
diff --git a/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp b/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp
--- a/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp
+++ b/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp
@@ -1318,8 +1318,8 @@
   return true;
 }
 
-bool PPCTTIImpl::isLSRCostLess(TargetTransformInfo::LSRCost &C1,
-                               TargetTransformInfo::LSRCost &C2) {
+bool PPCTTIImpl::isLSRCostLess(const TargetTransformInfo::LSRCost &C1,
+                               const TargetTransformInfo::LSRCost &C2) {
   // PowerPC default behaviour here is "instruction number 1st priority".
   // If LsrNoInsnsCost is set, call default implementation.
   if (!LsrNoInsnsCost)
diff --git a/llvm/lib/Target/SystemZ/SystemZTargetTransformInfo.h b/llvm/lib/Target/SystemZ/SystemZTargetTransformInfo.h
--- a/llvm/lib/Target/SystemZ/SystemZTargetTransformInfo.h
+++ b/llvm/lib/Target/SystemZ/SystemZTargetTransformInfo.h
@@ -59,8 +59,8 @@
   void getPeelingPreferences(Loop *L, ScalarEvolution &SE,
                              TTI::PeelingPreferences &PP);
 
-  bool isLSRCostLess(TargetTransformInfo::LSRCost &C1,
-                     TargetTransformInfo::LSRCost &C2);
+  bool isLSRCostLess(const TargetTransformInfo::LSRCost &C1,
+                     const TargetTransformInfo::LSRCost &C2);
   /// @}
 
   /// \name Vector TTI Implementations
diff --git a/llvm/lib/Target/SystemZ/SystemZTargetTransformInfo.cpp b/llvm/lib/Target/SystemZ/SystemZTargetTransformInfo.cpp
--- a/llvm/lib/Target/SystemZ/SystemZTargetTransformInfo.cpp
+++ b/llvm/lib/Target/SystemZ/SystemZTargetTransformInfo.cpp
@@ -339,8 +339,8 @@
   BaseT::getPeelingPreferences(L, SE, PP);
 }
 
-bool SystemZTTIImpl::isLSRCostLess(TargetTransformInfo::LSRCost &C1,
-                                   TargetTransformInfo::LSRCost &C2) {
+bool SystemZTTIImpl::isLSRCostLess(const TargetTransformInfo::LSRCost &C1,
+                                   const TargetTransformInfo::LSRCost &C2) {
   // SystemZ specific: check instruction count (first), and don't care about
   // ImmCost, since offsets are checked explicitly.
   return std::tie(C1.Insns, C1.NumRegs, C1.AddRecCost,
diff --git a/llvm/lib/Target/X86/X86TargetTransformInfo.h b/llvm/lib/Target/X86/X86TargetTransformInfo.h
--- a/llvm/lib/Target/X86/X86TargetTransformInfo.h
+++ b/llvm/lib/Target/X86/X86TargetTransformInfo.h
@@ -225,8 +225,8 @@
   InstructionCost getIntImmCostIntrin(Intrinsic::ID IID, unsigned Idx,
                                       const APInt &Imm, Type *Ty,
                                       TTI::TargetCostKind CostKind);
-  bool isLSRCostLess(TargetTransformInfo::LSRCost &C1,
-                     TargetTransformInfo::LSRCost &C2);
+  bool isLSRCostLess(const TargetTransformInfo::LSRCost &C1,
+                     const TargetTransformInfo::LSRCost &C2);
   bool canMacroFuseCmp();
   bool isLegalMaskedLoad(Type *DataType, Align Alignment);
   bool isLegalMaskedStore(Type *DataType, Align Alignment);
diff --git a/llvm/lib/Target/X86/X86TargetTransformInfo.cpp b/llvm/lib/Target/X86/X86TargetTransformInfo.cpp
--- a/llvm/lib/Target/X86/X86TargetTransformInfo.cpp
+++ b/llvm/lib/Target/X86/X86TargetTransformInfo.cpp
@@ -5188,8 +5188,8 @@
   return getGSVectorCost(Opcode, SrcVTy, Ptr, Alignment, AddressSpace);
 }
 
-bool X86TTIImpl::isLSRCostLess(TargetTransformInfo::LSRCost &C1,
-                               TargetTransformInfo::LSRCost &C2) {
+bool X86TTIImpl::isLSRCostLess(const TargetTransformInfo::LSRCost &C1,
+                               const TargetTransformInfo::LSRCost &C2) {
     // X86 specific here are "instruction number 1st priority".
     return std::tie(C1.Insns, C1.NumRegs, C1.AddRecCost,
                     C1.NumIVMuls, C1.NumBaseAdds,
diff --git a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
--- a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -1067,7 +1067,7 @@
     C.ScaleCost = 0;
   }
 
-  bool isLess(Cost &Other);
+  bool isLess(const Cost &Other);
 
   void Lose();
 
@@ -1464,7 +1464,7 @@
 }
 
 /// Choose the lower cost.
-bool Cost::isLess(Cost &Other) {
+bool Cost::isLess(const Cost &Other) {
   if (InsnsCost.getNumOccurrences() > 0 && InsnsCost &&
       C.Insns != Other.C.Insns)
     return C.Insns < Other.C.Insns;