diff --git a/llvm/include/llvm/Analysis/MemoryBuiltins.h b/llvm/include/llvm/Analysis/MemoryBuiltins.h
--- a/llvm/include/llvm/Analysis/MemoryBuiltins.h
+++ b/llvm/include/llvm/Analysis/MemoryBuiltins.h
@@ -19,7 +19,6 @@
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/Analysis/TargetFolder.h"
 #include "llvm/Analysis/TargetLibraryInfo.h"
-#include "llvm/IR/CallSite.h"
 #include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/InstVisitor.h"
 #include "llvm/IR/ValueHandle.h"
@@ -267,7 +266,7 @@
   // compute() should be used by external users.
   SizeOffsetType visitAllocaInst(AllocaInst &I);
   SizeOffsetType visitArgument(Argument &A);
-  SizeOffsetType visitCallSite(CallSite CS);
+  SizeOffsetType visitCallBase(CallBase &CB);
   SizeOffsetType visitConstantPointerNull(ConstantPointerNull&);
   SizeOffsetType visitExtractElementInst(ExtractElementInst &I);
   SizeOffsetType visitExtractValueInst(ExtractValueInst &I);
@@ -337,7 +336,7 @@
 
   // The individual instruction visitors should be treated as private.
   SizeOffsetEvalType visitAllocaInst(AllocaInst &I);
-  SizeOffsetEvalType visitCallSite(CallSite CS);
+  SizeOffsetEvalType visitCallBase(CallBase &CB);
   SizeOffsetEvalType visitExtractElementInst(ExtractElementInst &I);
   SizeOffsetEvalType visitExtractValueInst(ExtractValueInst &I);
   SizeOffsetEvalType visitGEPOperator(GEPOperator &GEP);
diff --git a/llvm/lib/Analysis/MemoryBuiltins.cpp b/llvm/lib/Analysis/MemoryBuiltins.cpp
--- a/llvm/lib/Analysis/MemoryBuiltins.cpp
+++ b/llvm/lib/Analysis/MemoryBuiltins.cpp
@@ -119,13 +119,13 @@
   if (LookThroughBitCast)
     V = V->stripPointerCasts();
 
-  ImmutableCallSite CS(V);
-  if (!CS.getInstruction())
+  const auto *CB = dyn_cast<CallBase>(V);
+  if (!CB)
     return nullptr;
 
-  IsNoBuiltin = CS.isNoBuiltin();
+  IsNoBuiltin = CB->isNoBuiltin();
 
-  if (const Function *Callee = CS.getCalledFunction())
+  if (const Function *Callee = CB->getCalledFunction())
     return Callee;
   return nullptr;
 }
@@ -227,8 +227,9 @@
 }
 
 static bool hasNoAliasAttr(const Value *V, bool LookThroughBitCast) {
-  ImmutableCallSite CS(LookThroughBitCast ? V->stripPointerCasts() : V);
-  return CS && CS.hasRetAttr(Attribute::NoAlias);
+  const auto *CB =
+      dyn_cast<CallBase>(LookThroughBitCast ? V->stripPointerCasts() : V);
+  return CB && CB->hasRetAttr(Attribute::NoAlias);
 }
 
 /// Tests if a value is a call or invoke to a library function that
@@ -682,21 +683,21 @@
   return std::make_pair(align(Size, A.getParamAlignment()), Zero);
 }
 
-SizeOffsetType ObjectSizeOffsetVisitor::visitCallSite(CallSite CS) {
-  Optional<AllocFnsTy> FnData = getAllocationSize(CS.getInstruction(), TLI);
+SizeOffsetType ObjectSizeOffsetVisitor::visitCallBase(CallBase &CB) {
+  Optional<AllocFnsTy> FnData = getAllocationSize(&CB, TLI);
   if (!FnData)
     return unknown();
 
   // Handle strdup-like functions separately.
   if (FnData->AllocTy == StrDupLike) {
-    APInt Size(IntTyBits, GetStringLength(CS.getArgument(0)));
+    APInt Size(IntTyBits, GetStringLength(CB.getArgOperand(0)));
     if (!Size)
       return unknown();
 
     // Strndup limits strlen.
     if (FnData->FstParam > 0) {
       ConstantInt *Arg =
-          dyn_cast<ConstantInt>(CS.getArgument(FnData->FstParam));
+          dyn_cast<ConstantInt>(CB.getArgOperand(FnData->FstParam));
       if (!Arg)
         return unknown();
 
@@ -707,7 +708,7 @@
     return std::make_pair(Size, Zero);
   }
 
-  ConstantInt *Arg = dyn_cast<ConstantInt>(CS.getArgument(FnData->FstParam));
+  ConstantInt *Arg = dyn_cast<ConstantInt>(CB.getArgOperand(FnData->FstParam));
   if (!Arg)
     return unknown();
 
@@ -719,7 +720,7 @@
   if (FnData->SndParam < 0)
     return std::make_pair(Size, Zero);
 
-  Arg = dyn_cast<ConstantInt>(CS.getArgument(FnData->SndParam));
+  Arg = dyn_cast<ConstantInt>(CB.getArgOperand(FnData->SndParam));
   if (!Arg)
     return unknown();
 
@@ -947,8 +948,8 @@
   return std::make_pair(Size, Zero);
 }
 
-SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitCallSite(CallSite CS) {
-  Optional<AllocFnsTy> FnData = getAllocationSize(CS.getInstruction(), TLI);
+SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitCallBase(CallBase &CB) {
+  Optional<AllocFnsTy> FnData = getAllocationSize(&CB, TLI);
   if (!FnData)
     return unknown();
 
@@ -958,12 +959,12 @@
     return unknown();
   }
 
-  Value *FirstArg = CS.getArgument(FnData->FstParam);
+  Value *FirstArg = CB.getArgOperand(FnData->FstParam);
   FirstArg = Builder.CreateZExtOrTrunc(FirstArg, IntTy);
   if (FnData->SndParam < 0)
     return std::make_pair(FirstArg, Zero);
 
-  Value *SecondArg = CS.getArgument(FnData->SndParam);
+  Value *SecondArg = CB.getArgOperand(FnData->SndParam);
   SecondArg = Builder.CreateZExtOrTrunc(SecondArg, IntTy);
   Value *Size = Builder.CreateMul(FirstArg, SecondArg);
   return std::make_pair(Size, Zero);