Index: llvm/trunk/include/llvm/IR/Function.h
===================================================================
--- llvm/trunk/include/llvm/IR/Function.h
+++ llvm/trunk/include/llvm/IR/Function.h
@@ -509,22 +509,13 @@
   /// Requires that this has no function body.
   void stealArgumentListFrom(Function &Src);
 
-  /// Get the underlying elements of the Function... the basic block list is
-  /// empty for external functions.
-  ///
-  const ArgumentListType &getArgumentList() const {
-    CheckLazyArguments();
-    return ArgumentList;
-  }
-  ArgumentListType &getArgumentList() {
-    CheckLazyArguments();
-    return ArgumentList;
-  }
-
   static ArgumentListType Function::*getSublistAccess(Argument*) {
     return &Function::ArgumentList;
   }
 
+  /// Get the underlying elements of the Function... the basic block list is
+  /// empty for external functions.
+  ///
   const BasicBlockListType &getBasicBlockList() const { return BasicBlocks; }
         BasicBlockListType &getBasicBlockList()       { return BasicBlocks; }
 
Index: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
===================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -8000,7 +8000,7 @@
   // entries as we have arguments.
   enum StaticAllocaInfo { Unknown, Clobbered, Elidable };
   SmallDenseMap<const AllocaInst *, StaticAllocaInfo, 8> StaticAllocas;
-  unsigned NumArgs = FuncInfo->Fn->getArgumentList().size();
+  unsigned NumArgs = FuncInfo->Fn->arg_size();
   StaticAllocas.reserve(NumArgs * 2);
 
   auto GetInfoIfStaticAlloca = [&](const Value *V) -> StaticAllocaInfo * {
Index: llvm/trunk/lib/Target/AArch64/AArch64CallLowering.cpp
===================================================================
--- llvm/trunk/lib/Target/AArch64/AArch64CallLowering.cpp
+++ llvm/trunk/lib/Target/AArch64/AArch64CallLowering.cpp
@@ -238,7 +238,6 @@
 bool AArch64CallLowering::lowerFormalArguments(MachineIRBuilder &MIRBuilder,
                                                const Function &F,
                                                ArrayRef<unsigned> VRegs) const {
-  auto &Args = F.getArgumentList();
   MachineFunction &MF = MIRBuilder.getMF();
   MachineBasicBlock &MBB = MIRBuilder.getMBB();
   MachineRegisterInfo &MRI = MF.getRegInfo();
@@ -246,7 +245,7 @@
 
   SmallVector<ArgInfo, 8> SplitArgs;
   unsigned i = 0;
-  for (auto &Arg : Args) {
+  for (auto &Arg : F.args()) {
     ArgInfo OrigArg{VRegs[i], Arg.getType()};
     setArgFlags(OrigArg, i + 1, DL, F);
     bool Split = false;
Index: llvm/trunk/lib/Target/ARM/ARMCallLowering.cpp
===================================================================
--- llvm/trunk/lib/Target/ARM/ARMCallLowering.cpp
+++ llvm/trunk/lib/Target/ARM/ARMCallLowering.cpp
@@ -337,8 +337,7 @@
   if (Subtarget->useSoftFloat() || !Subtarget->hasVFP2())
     return false;
 
-  auto &Args = F.getArgumentList();
-  for (auto &Arg : Args)
+  for (auto &Arg : F.args())
     if (!isSupportedType(DL, TLI, Arg.getType()))
       return false;
 
@@ -347,7 +346,7 @@
 
   SmallVector<ArgInfo, 8> ArgInfos;
   unsigned Idx = 0;
-  for (auto &Arg : Args) {
+  for (auto &Arg : F.args()) {
     ArgInfo AInfo(VRegs[Idx], Arg.getType());
     setArgFlags(AInfo, Idx + 1, DL, F);
     splitToValueTypes(AInfo, ArgInfos, DL, MF.getRegInfo());
Index: llvm/trunk/lib/Target/AVR/AVRInstrumentFunctions.cpp
===================================================================
--- llvm/trunk/lib/Target/AVR/AVRInstrumentFunctions.cpp
+++ llvm/trunk/lib/Target/AVR/AVRInstrumentFunctions.cpp
@@ -96,7 +96,7 @@
   Value *FunctionName = CreateStringPtr(BB, F.getName());
 
   Value *Args[] = {FunctionName,
-                   ConstantInt::get(I16, F.getArgumentList().size())};
+                   ConstantInt::get(I16, F.arg_size())};
   CallInst::Create(Fn, Args, "", &BB);
 }
 
Index: llvm/trunk/lib/Target/Mips/MipsOs16.cpp
===================================================================
--- llvm/trunk/lib/Target/Mips/MipsOs16.cpp
+++ llvm/trunk/lib/Target/Mips/MipsOs16.cpp
@@ -57,7 +57,7 @@
     ;
   }
   if (F.arg_size() >=1) {
-    Argument &Arg = F.getArgumentList().front();
+    Argument &Arg = *F.arg_begin();
     switch (Arg.getType()->getTypeID()) {
     case Type::FloatTyID:
     case Type::DoubleTyID:
Index: llvm/trunk/lib/Target/PowerPC/PPCISelLowering.cpp
===================================================================
--- llvm/trunk/lib/Target/PowerPC/PPCISelLowering.cpp
+++ llvm/trunk/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -4111,7 +4111,7 @@
 
 static bool
 hasSameArgumentList(const Function *CallerFn, ImmutableCallSite *CS) {
-  if (CS->arg_size() != CallerFn->getArgumentList().size())
+  if (CS->arg_size() != CallerFn->arg_size())
     return false;
 
   ImmutableCallSite::arg_iterator CalleeArgIter = CS->arg_begin();
Index: llvm/trunk/lib/Target/X86/X86CallLowering.cpp
===================================================================
--- llvm/trunk/lib/Target/X86/X86CallLowering.cpp
+++ llvm/trunk/lib/Target/X86/X86CallLowering.cpp
@@ -179,7 +179,7 @@
 
   SmallVector<ArgInfo, 8> SplitArgs;
   unsigned Idx = 0;
-  for (auto &Arg : F.getArgumentList()) {
+  for (auto &Arg : F.args()) {
     ArgInfo OrigArg(VRegs[Idx], Arg.getType());
     setArgFlags(OrigArg, Idx + 1, DL, F);
     LLT Ty = MRI.getType(VRegs[Idx]);
Index: llvm/trunk/lib/Transforms/Coroutines/CoroElide.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Coroutines/CoroElide.cpp
+++ llvm/trunk/lib/Transforms/Coroutines/CoroElide.cpp
@@ -92,7 +92,7 @@
 
 // Given a resume function @f.resume(%f.frame* %frame), returns %f.frame type.
 static Type *getFrameType(Function *Resume) {
-  auto *ArgType = Resume->getArgumentList().front().getType();
+  auto *ArgType = Resume->arg_begin()->getType();
   return cast<PointerType>(ArgType)->getElementType();
 }
 
Index: llvm/trunk/lib/Transforms/Coroutines/CoroFrame.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Coroutines/CoroFrame.cpp
+++ llvm/trunk/lib/Transforms/Coroutines/CoroFrame.cpp
@@ -707,7 +707,7 @@
 
   // Collect the spills for arguments and other not-materializable values.
   Spills.clear();
-  for (Argument &A : F.getArgumentList())
+  for (Argument &A : F.args())
     for (User *U : A.users())
       if (Checker.isDefinitionAcrossSuspend(A, U))
         Spills.emplace_back(&A, U);
Index: llvm/trunk/lib/Transforms/Coroutines/CoroSplit.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Coroutines/CoroSplit.cpp
+++ llvm/trunk/lib/Transforms/Coroutines/CoroSplit.cpp
@@ -223,7 +223,7 @@
   // Replace all args with undefs. The buildCoroutineFrame algorithm already
   // rewritten access to the args that occurs after suspend points with loads
   // and stores to/from the coroutine frame.
-  for (Argument &A : F.getArgumentList())
+  for (Argument &A : F.args())
     VMap[&A] = UndefValue::get(A.getType());
 
   SmallVector<ReturnInst *, 4> Returns;
@@ -264,7 +264,7 @@
   IRBuilder<> Builder(&NewF->getEntryBlock().front());
 
   // Remap frame pointer.
-  Argument *NewFramePtr = &NewF->getArgumentList().front();
+  Argument *NewFramePtr = &*NewF->arg_begin();
   Value *OldFramePtr = cast<Value>(VMap[Shape.FramePtr]);
   NewFramePtr->takeName(OldFramePtr);
   OldFramePtr->replaceAllUsesWith(NewFramePtr);
Index: llvm/trunk/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
+++ llvm/trunk/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
@@ -580,8 +580,7 @@
     Function::arg_iterator AI = F->arg_begin(); ++AI;
     for (unsigned N = FT->getNumParams(); N != 0; ++AI, --N)
       Args.push_back(&*AI);
-    CallInst *CI =
-        CallInst::Create(&F->getArgumentList().front(), Args, "", BB);
+    CallInst *CI = CallInst::Create(&*F->arg_begin(), Args, "", BB);
     ReturnInst *RI;
     if (FT->getReturnType()->isVoidTy())
       RI = ReturnInst::Create(*Ctx, BB);
@@ -595,7 +594,7 @@
     DFSanVisitor(DFSF).visitCallInst(*CI);
     if (!FT->getReturnType()->isVoidTy())
       new StoreInst(DFSF.getShadow(RI->getReturnValue()),
-                    &F->getArgumentList().back(), RI);
+                    &*std::prev(F->arg_end()), RI);
   }
 
   return C;
@@ -906,7 +905,7 @@
         break;
       }
       case DataFlowSanitizer::IA_Args: {
-        unsigned ArgIdx = A->getArgNo() + F->getArgumentList().size() / 2;
+        unsigned ArgIdx = A->getArgNo() + F->arg_size() / 2;
         Function::arg_iterator i = F->arg_begin();
         while (ArgIdx--)
           ++i;
Index: llvm/trunk/lib/Transforms/Utils/InlineFunction.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Utils/InlineFunction.cpp
+++ llvm/trunk/lib/Transforms/Utils/InlineFunction.cpp
@@ -1603,7 +1603,7 @@
     // matches up the formal to the actual argument values.
     CallSite::arg_iterator AI = CS.arg_begin();
     unsigned ArgNo = 0;
-    for (Function::const_arg_iterator I = CalledFunc->arg_begin(),
+    for (Function::arg_iterator I = CalledFunc->arg_begin(),
          E = CalledFunc->arg_end(); I != E; ++I, ++AI, ++ArgNo) {
       Value *ActualArg = *AI;
 
Index: llvm/trunk/unittests/IR/ValueTest.cpp
===================================================================
--- llvm/trunk/unittests/IR/ValueTest.cpp
+++ llvm/trunk/unittests/IR/ValueTest.cpp
@@ -40,7 +40,7 @@
   Function *F = M->getFunction("f");
 
   EXPECT_FALSE(F->isUsedInBasicBlock(&F->front()));
-  EXPECT_TRUE((++F->arg_begin())->isUsedInBasicBlock(&F->front()));
+  EXPECT_TRUE(std::next(F->arg_begin())->isUsedInBasicBlock(&F->front()));
   EXPECT_TRUE(F->arg_begin()->isUsedInBasicBlock(&F->front()));
 }
 
Index: llvm/trunk/unittests/Transforms/Utils/IntegerDivision.cpp
===================================================================
--- llvm/trunk/unittests/Transforms/Utils/IntegerDivision.cpp
+++ llvm/trunk/unittests/Transforms/Utils/IntegerDivision.cpp
@@ -29,7 +29,7 @@
   Function *F = Function::Create(FunctionType::get(Builder.getInt32Ty(),
                                                    ArgTys, false),
                                  GlobalValue::ExternalLinkage, "F", &M);
-  assert(F->getArgumentList().size() == 2);
+  assert(F->arg_size() == 2);
 
   BasicBlock *BB = BasicBlock::Create(C, "", F);
   Builder.SetInsertPoint(BB);
@@ -59,7 +59,7 @@
   Function *F = Function::Create(FunctionType::get(Builder.getInt32Ty(),
                                                    ArgTys, false),
                                  GlobalValue::ExternalLinkage, "F", &M);
-  assert(F->getArgumentList().size() == 2);
+  assert(F->arg_size() == 2);
 
   BasicBlock *BB = BasicBlock::Create(C, "", F);
   Builder.SetInsertPoint(BB);
@@ -89,7 +89,7 @@
   Function *F = Function::Create(FunctionType::get(Builder.getInt32Ty(),
                                                    ArgTys, false),
                                  GlobalValue::ExternalLinkage, "F", &M);
-  assert(F->getArgumentList().size() == 2);
+  assert(F->arg_size() == 2);
 
   BasicBlock *BB = BasicBlock::Create(C, "", F);
   Builder.SetInsertPoint(BB);
@@ -119,7 +119,7 @@
   Function *F = Function::Create(FunctionType::get(Builder.getInt32Ty(),
                                                    ArgTys, false),
                                  GlobalValue::ExternalLinkage, "F", &M);
-  assert(F->getArgumentList().size() == 2);
+  assert(F->arg_size() == 2);
 
   BasicBlock *BB = BasicBlock::Create(C, "", F);
   Builder.SetInsertPoint(BB);
@@ -150,7 +150,7 @@
   Function *F = Function::Create(FunctionType::get(Builder.getInt64Ty(),
                                                    ArgTys, false),
                                  GlobalValue::ExternalLinkage, "F", &M);
-  assert(F->getArgumentList().size() == 2);
+  assert(F->arg_size() == 2);
 
   BasicBlock *BB = BasicBlock::Create(C, "", F);
   Builder.SetInsertPoint(BB);
@@ -180,7 +180,7 @@
   Function *F = Function::Create(FunctionType::get(Builder.getInt64Ty(),
                                                    ArgTys, false),
                                  GlobalValue::ExternalLinkage, "F", &M);
-  assert(F->getArgumentList().size() == 2);
+  assert(F->arg_size() == 2);
 
   BasicBlock *BB = BasicBlock::Create(C, "", F);
   Builder.SetInsertPoint(BB);
@@ -210,7 +210,7 @@
   Function *F = Function::Create(FunctionType::get(Builder.getInt64Ty(),
                                                    ArgTys, false),
                                  GlobalValue::ExternalLinkage, "F", &M);
-  assert(F->getArgumentList().size() == 2);
+  assert(F->arg_size() == 2);
 
   BasicBlock *BB = BasicBlock::Create(C, "", F);
   Builder.SetInsertPoint(BB);
@@ -240,7 +240,7 @@
   Function *F = Function::Create(FunctionType::get(Builder.getInt64Ty(),
                                                    ArgTys, false),
                                  GlobalValue::ExternalLinkage, "F", &M);
-  assert(F->getArgumentList().size() == 2);
+  assert(F->arg_size() == 2);
 
   BasicBlock *BB = BasicBlock::Create(C, "", F);
   Builder.SetInsertPoint(BB);