diff --git a/lib/CodeGen/GlobalISel/LegalizerInfo.cpp b/lib/CodeGen/GlobalISel/LegalizerInfo.cpp
index 30acac14bc5..dfc4034e11a 100644
--- a/lib/CodeGen/GlobalISel/LegalizerInfo.cpp
+++ b/lib/CodeGen/GlobalISel/LegalizerInfo.cpp
@@ -446,8 +446,8 @@ LegalizeRuleSet &LegalizerInfo::getActionDefinitionsBuilder(
   assert(!llvm::empty(Opcodes) && Opcodes.begin() + 1 != Opcodes.end() &&
          "Initializer list must have at least two opcodes");
 
-  for (auto I = Opcodes.begin() + 1, E = Opcodes.end(); I != E; ++I)
-    aliasActionDefinitions(Representative, *I);
+  for (unsigned Op : llvm::drop_begin(Opcodes))
+    aliasActionDefinitions(Representative, Op);
 
   auto &Return = getActionDefinitionsBuilder(Representative);
   Return.setIsAliasedByAnother();
diff --git a/lib/CodeGen/GlobalISel/Localizer.cpp b/lib/CodeGen/GlobalISel/Localizer.cpp
index 30c00c63f6f..d45fdae43f0 100644
--- a/lib/CodeGen/GlobalISel/Localizer.cpp
+++ b/lib/CodeGen/GlobalISel/Localizer.cpp
@@ -82,8 +82,7 @@ bool Localizer::localizeInterBlock(MachineFunction &MF,
   // we start doing CSE across blocks.
   auto &MBB = MF.front();
   auto &TL = *MF.getSubtarget().getTargetLowering();
-  for (auto RI = MBB.rbegin(), RE = MBB.rend(); RI != RE; ++RI) {
-    MachineInstr &MI = *RI;
+  for (MachineInstr &MI : llvm::reverse(MBB)) {
     if (!TL.shouldLocalize(MI, TTI))
       continue;
     LLVM_DEBUG(dbgs() << "Should localize: " << MI);
diff --git a/lib/CodeGen/LiveVariables.cpp b/lib/CodeGen/LiveVariables.cpp
index 8201baf220f..e0ef38dbc72 100644
--- a/lib/CodeGen/LiveVariables.cpp
+++ b/lib/CodeGen/LiveVariables.cpp
@@ -774,13 +774,12 @@ void LiveVariables::addNewBlock(MachineBasicBlock *BB,
 
   // Record all vreg defs and kills of all instructions in SuccBB.
   for (; BBI != BBE; ++BBI) {
-    for (MachineInstr::mop_iterator I = BBI->operands_begin(),
-         E = BBI->operands_end(); I != E; ++I) {
-      if (I->isReg() && Register::isVirtualRegister(I->getReg())) {
-        if (I->isDef())
-          Defs.insert(I->getReg());
-        else if (I->isKill())
-          Kills.insert(I->getReg());
+    for (const MachineOperand &Op : BBI->operands()) {
+      if (Op.isReg() && Register::isVirtualRegister(Op.getReg())) {
+        if (Op.isDef())
+          Defs.insert(Op.getReg());
+        else if (Op.isKill())
+          Kills.insert(Op.getReg());
       }
     }
   }
diff --git a/lib/CodeGen/MachineRegisterInfo.cpp b/lib/CodeGen/MachineRegisterInfo.cpp
index b789f9d5670..d7444ece6f6 100644
--- a/lib/CodeGen/MachineRegisterInfo.cpp
+++ b/lib/CodeGen/MachineRegisterInfo.cpp
@@ -531,13 +531,10 @@ bool MachineRegisterInfo::isConstantPhysReg(MCRegister PhysReg) const {
 /// deleted during LiveDebugVariables analysis.
 void MachineRegisterInfo::markUsesInDebugValueAsUndef(Register Reg) const {
   // Mark any DBG_VALUE that uses Reg as undef (but don't delete it.)
-  MachineRegisterInfo::use_instr_iterator nextI;
-  for (use_instr_iterator I = use_instr_begin(Reg), E = use_instr_end();
-       I != E; I = nextI) {
-    nextI = std::next(I);  // I is invalidated by the setReg
-    MachineInstr *UseMI = &*I;
-    if (UseMI->isDebugValue())
-      UseMI->getDebugOperandForReg(Reg)->setReg(0U);
+  // We use make_early_inc_range because setReg invalidates the iterator.
+  for (MachineInstr &UseMI : llvm::make_early_inc_range(use_instructions(Reg))) {
+    if (UseMI.isDebugValue())
+      UseMI.getDebugOperandForReg(Reg)->setReg(0U);
   }
 }
 
diff --git a/lib/CodeGen/RDFLiveness.cpp b/lib/CodeGen/RDFLiveness.cpp
index 9a920ebad94..0580a327777 100644
--- a/lib/CodeGen/RDFLiveness.cpp
+++ b/lib/CodeGen/RDFLiveness.cpp
@@ -238,8 +238,8 @@ NodeList Liveness::getAllReachingDefs(RegisterRef RefRR,
              [this](auto A, auto B) { return MDT.properlyDominates(A, B); });
 
   std::vector<NodeId> TmpInst;
-  for (auto I = TmpBB.rbegin(), E = TmpBB.rend(); I != E; ++I) {
-    auto &Bucket = Blocks[*I];
+  for (MachineBasicBlock *MBB : llvm::reverse(TmpBB)) {
+    auto &Bucket = Blocks[MBB];
     TmpInst.insert(TmpInst.end(), Bucket.rbegin(), Bucket.rend());
   }
 
@@ -931,13 +931,12 @@ void Liveness::resetKills(MachineBasicBlock *B) {
   for (auto SI : B->successors())
     CopyLiveIns(SI, Live);
 
-  for (auto I = B->rbegin(), E = B->rend(); I != E; ++I) {
-    MachineInstr *MI = &*I;
-    if (MI->isDebugInstr())
+  for (MachineInstr &MI : llvm::reverse(*B)) {
+    if (MI.isDebugInstr())
       continue;
 
-    MI->clearKillInfo();
-    for (auto &Op : MI->operands()) {
+    MI.clearKillInfo();
+    for (auto &Op : MI.operands()) {
       // An implicit def of a super-register may not necessarily start a
       // live range of it, since an implicit use could be used to keep parts
       // of it live. Instead of analyzing the implicit operands, ignore
@@ -950,7 +949,7 @@ void Liveness::resetKills(MachineBasicBlock *B) {
       for (MCSubRegIterator SR(R, &TRI, true); SR.isValid(); ++SR)
         Live.reset(*SR);
     }
-    for (auto &Op : MI->operands()) {
+    for (auto &Op : MI.operands()) {
       if (!Op.isReg() || !Op.isUse() || Op.isUndef())
         continue;
       Register R = Op.getReg();
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
index 4cbf8a83e8c..c78d74585cb 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
@@ -896,12 +896,10 @@ static void DumpNodes(const SDNode *N, unsigned indent, const SelectionDAG *G) {
 LLVM_DUMP_METHOD void SelectionDAG::dump() const {
   dbgs() << "SelectionDAG has " << AllNodes.size() << " nodes:\n";
 
-  for (allnodes_const_iterator I = allnodes_begin(), E = allnodes_end();
-       I != E; ++I) {
-    const SDNode *N = &*I;
-    if (!N->hasOneUse() && N != getRoot().getNode() &&
-        (!shouldPrintInline(*N, this) || N->use_empty()))
-      DumpNodes(N, 2, this);
+  for (const SDNode &N : allnodes()) {
+    if (!N.hasOneUse() && &N != getRoot().getNode() &&
+        (!shouldPrintInline(N, this) || N.use_empty()))
+      DumpNodes(&N, 2, this);
   }
 
   if (getRoot().getNode()) DumpNodes(getRoot().getNode(), 2, this);
diff --git a/lib/CodeGen/SplitKit.cpp b/lib/CodeGen/SplitKit.cpp
index ced8de4c25a..22cd63e3215 100644
--- a/lib/CodeGen/SplitKit.cpp
+++ b/lib/CodeGen/SplitKit.cpp
@@ -94,10 +94,10 @@ InsertPointAnalysis::computeLastInsertPoint(const LiveInterval &CurLI,
     // instructions in the block.
     if (ExceptionalSuccessors.empty())
       return LIP.first;
-    for (auto I = MBB.rbegin(), E = MBB.rend(); I != E; ++I) {
-      if ((EHPadSuccessor && I->isCall()) ||
-          I->getOpcode() == TargetOpcode::INLINEASM_BR) {
-        LIP.second = LIS.getInstructionIndex(*I);
+    for (const MachineInstr &MI : llvm::reverse(MBB)) {
+      if ((EHPadSuccessor && MI.isCall()) ||
+          MI.getOpcode() == TargetOpcode::INLINEASM_BR) {
+        LIP.second = LIS.getInstructionIndex(MI);
         break;
       }
     }
@@ -810,8 +810,8 @@ void SplitEditor::removeBackCopies(SmallVectorImpl<VNInfo*> &Copies) {
   RegAssignMap::iterator AssignI;
   AssignI.setMap(RegAssign);
 
-  for (unsigned i = 0, e = Copies.size(); i != e; ++i) {
-    SlotIndex Def = Copies[i]->def;
+  for (const VNInfo *C : Copies) {
+    SlotIndex Def = C->def;
     MachineInstr *MI = LIS.getInstructionFromIndex(Def);
     assert(MI && "No instruction for back-copy");
 
diff --git a/lib/CodeGen/UnreachableBlockElim.cpp b/lib/CodeGen/UnreachableBlockElim.cpp
index f5dc589a98c..c9a19948ff2 100644
--- a/lib/CodeGen/UnreachableBlockElim.cpp
+++ b/lib/CodeGen/UnreachableBlockElim.cpp
@@ -114,25 +114,23 @@ bool UnreachableMachineBlockElim::runOnMachineFunction(MachineFunction &F) {
   // Loop over all dead blocks, remembering them and deleting all instructions
   // in them.
   std::vector<MachineBasicBlock*> DeadBlocks;
-  for (MachineFunction::iterator I = F.begin(), E = F.end(); I != E; ++I) {
-    MachineBasicBlock *BB = &*I;
-
+  for (MachineBasicBlock &BB : F) {
     // Test for deadness.
-    if (!Reachable.count(BB)) {
-      DeadBlocks.push_back(BB);
+    if (!Reachable.count(&BB)) {
+      DeadBlocks.push_back(&BB);
 
       // Update dominator and loop info.
-      if (MLI) MLI->removeBlock(BB);
-      if (MDT && MDT->getNode(BB)) MDT->eraseNode(BB);
+      if (MLI) MLI->removeBlock(&BB);
+      if (MDT && MDT->getNode(&BB)) MDT->eraseNode(&BB);
 
-      while (BB->succ_begin() != BB->succ_end()) {
-        MachineBasicBlock* succ = *BB->succ_begin();
+      while (BB.succ_begin() != BB.succ_end()) {
+        MachineBasicBlock* succ = *BB.succ_begin();
 
         MachineBasicBlock::iterator start = succ->begin();
         while (start != succ->end() && start->isPHI()) {
           for (unsigned i = start->getNumOperands() - 1; i >= 2; i-=2)
             if (start->getOperand(i).isMBB() &&
-                start->getOperand(i).getMBB() == BB) {
+                start->getOperand(i).getMBB() == &BB) {
               start->RemoveOperand(i);
               start->RemoveOperand(i-1);
             }
@@ -140,7 +138,7 @@ bool UnreachableMachineBlockElim::runOnMachineFunction(MachineFunction &F) {
           start++;
         }
 
-        BB->removeSuccessor(BB->succ_begin());
+        BB.removeSuccessor(BB.succ_begin());
       }
     }
   }