diff --git a/lib/CodeGen/RegAllocPBQP.cpp b/lib/CodeGen/RegAllocPBQP.cpp
index 7c5af1a0c56..73290f15c43 100644
--- a/lib/CodeGen/RegAllocPBQP.cpp
+++ b/lib/CodeGen/RegAllocPBQP.cpp
@@ -703,9 +703,8 @@ void RegAllocPBQP::spillVReg(Register VReg,
 
   // Copy any newly inserted live intervals into the list of regs to
   // allocate.
-  for (LiveRangeEdit::iterator I = LRE.begin(), E = LRE.end();
-       I != E; ++I) {
-    const LiveInterval &LI = LIS.getInterval(*I);
+  for (const Register &R : LRE) {
+    const LiveInterval &LI = LIS.getInterval(R);
     assert(!LI.empty() && "Empty spill range.");
     LLVM_DEBUG(dbgs() << printReg(LI.reg(), &TRI) << " ");
     VRegsToAlloc.insert(LI.reg());
@@ -759,10 +758,8 @@ void RegAllocPBQP::finalizeAlloc(MachineFunction &MF,
   MachineRegisterInfo &MRI = MF.getRegInfo();
 
   // First allocate registers for the empty intervals.
-  for (RegSet::const_iterator
-         I = EmptyIntervalVRegs.begin(), E = EmptyIntervalVRegs.end();
-         I != E; ++I) {
-    LiveInterval &LI = LIS.getInterval(*I);
+  for (const Register &R : EmptyIntervalVRegs) {
+    LiveInterval &LI = LIS.getInterval(R);
 
     Register PReg = MRI.getSimpleHint(LI.reg());
 
diff --git a/lib/CodeGen/RegisterCoalescer.cpp b/lib/CodeGen/RegisterCoalescer.cpp
index 5f770d6b0bc..3e4b2ba0c1a 100644
--- a/lib/CodeGen/RegisterCoalescer.cpp
+++ b/lib/CodeGen/RegisterCoalescer.cpp
@@ -3877,21 +3877,20 @@ RegisterCoalescer::copyCoalesceInMBB(MachineBasicBlock *MBB) {
     // are not inherently easier to resolve, but slightly preferable until we
     // have local live range splitting. In particular this is required by
     // cmp+jmp macro fusion.
-    for (MachineBasicBlock::iterator MII = MBB->begin(), E = MBB->end();
-         MII != E; ++MII) {
-      if (!MII->isCopyLike())
+    for (MachineInstr &MI : *MBB) {
+      if (!MI.isCopyLike())
         continue;
-      bool ApplyTerminalRule = applyTerminalRule(*MII);
-      if (isLocalCopy(&(*MII), LIS)) {
+      bool ApplyTerminalRule = applyTerminalRule(MI);
+      if (isLocalCopy(&MI, LIS)) {
         if (ApplyTerminalRule)
-          LocalTerminals.push_back(&(*MII));
+          LocalTerminals.push_back(&MI);
         else
-          LocalWorkList.push_back(&(*MII));
+          LocalWorkList.push_back(&MI);
       } else {
         if (ApplyTerminalRule)
-          GlobalTerminals.push_back(&(*MII));
+          GlobalTerminals.push_back(&MI);
         else
-          WorkList.push_back(&(*MII));
+          WorkList.push_back(&MI);
       }
     }
     // Append the copies evicted by the terminal rule at the end of the list.
@@ -3935,10 +3934,9 @@ void RegisterCoalescer::joinAllIntervals() {
 
   std::vector<MBBPriorityInfo> MBBs;
   MBBs.reserve(MF->size());
-  for (MachineFunction::iterator I = MF->begin(), E = MF->end(); I != E; ++I) {
-    MachineBasicBlock *MBB = &*I;
-    MBBs.push_back(MBBPriorityInfo(MBB, Loops->getLoopDepth(MBB),
-                                   JoinSplitEdges && isSplitEdge(MBB)));
+  for (MachineBasicBlock &MBB : *MF) {
+    MBBs.push_back(MBBPriorityInfo(&MBB, Loops->getLoopDepth(&MBB),
+                                   JoinSplitEdges && isSplitEdge(&MBB)));
   }
   array_pod_sort(MBBs.begin(), MBBs.end(), compareMBBPriority);
 
diff --git a/lib/CodeGen/RegisterScavenging.cpp b/lib/CodeGen/RegisterScavenging.cpp
index a833895c115..e885bfd5956 100644
--- a/lib/CodeGen/RegisterScavenging.cpp
+++ b/lib/CodeGen/RegisterScavenging.cpp
@@ -167,13 +167,12 @@ void RegScavenger::forward() {
 
   MachineInstr &MI = *MBBI;
 
-  for (SmallVectorImpl<ScavengedInfo>::iterator I = Scavenged.begin(),
-         IE = Scavenged.end(); I != IE; ++I) {
-    if (I->Restore != &MI)
+  for (ScavengedInfo &I : Scavenged) {
+    if (I.Restore != &MI)
       continue;
 
-    I->Reg = 0;
-    I->Restore = nullptr;
+    I.Reg = 0;
+    I.Restore = nullptr;
   }
 
   if (MI.isDebugInstr())
diff --git a/lib/CodeGen/ShadowStackGCLowering.cpp b/lib/CodeGen/ShadowStackGCLowering.cpp
index f2111a021ef..36752ef8652 100644
--- a/lib/CodeGen/ShadowStackGCLowering.cpp
+++ b/lib/CodeGen/ShadowStackGCLowering.cpp
@@ -238,8 +238,8 @@ void ShadowStackGCLowering::CollectRoots(Function &F) {
 
   SmallVector<std::pair<CallInst *, AllocaInst *>, 16> MetaRoots;
 
-  for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
-    for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E;)
+  for (BasicBlock &BB : F)
+    for (BasicBlock::iterator II = BB.begin(), E = BB.end(); II != E;)
       if (IntrinsicInst *CI = dyn_cast<IntrinsicInst>(II++))
         if (Function *F = CI->getCalledFunction())
           if (F->getIntrinsicID() == Intrinsic::gcroot) {
diff --git a/lib/CodeGen/SlotIndexes.cpp b/lib/CodeGen/SlotIndexes.cpp
index d2bfdc663ed..c72bcf2c84d 100644
--- a/lib/CodeGen/SlotIndexes.cpp
+++ b/lib/CodeGen/SlotIndexes.cpp
@@ -248,12 +248,11 @@ void SlotIndexes::repairIndexesInRange(MachineBasicBlock *MBB,
 
 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
 LLVM_DUMP_METHOD void SlotIndexes::dump() const {
-  for (IndexList::const_iterator itr = indexList.begin();
-       itr != indexList.end(); ++itr) {
-    dbgs() << itr->getIndex() << " ";
+  for (const IndexListEntry &ILE : indexList) {
+    dbgs() << ILE.getIndex() << " ";
 
-    if (itr->getInstr()) {
-      dbgs() << *itr->getInstr();
+    if (ILE.getInstr()) {
+      dbgs() << *ILE.getInstr();
     } else {
       dbgs() << "\n";
     }
@@ -280,4 +279,3 @@ LLVM_DUMP_METHOD void SlotIndex::dump() const {
   dbgs() << "\n";
 }
 #endif
-
diff --git a/lib/CodeGen/SpillPlacement.cpp b/lib/CodeGen/SpillPlacement.cpp
index 6f91092097d..91da5e49713 100644
--- a/lib/CodeGen/SpillPlacement.cpp
+++ b/lib/CodeGen/SpillPlacement.cpp
@@ -121,9 +121,9 @@ struct SpillPlacement::Node {
     SumLinkWeights += w;
 
     // There can be multiple links to the same bundle, add them up.
-    for (LinkVector::iterator I = Links.begin(), E = Links.end(); I != E; ++I)
-      if (I->second == b) {
-        I->first += w;
+    for (std::pair<BlockFrequency, unsigned> &L : Links)
+      if (L.second == b) {
+        L.first += w;
         return;
       }
     // This must be the first link to b.
@@ -153,11 +153,11 @@ struct SpillPlacement::Node {
     // Compute the weighted sum of inputs.
     BlockFrequency SumN = BiasN;
     BlockFrequency SumP = BiasP;
-    for (LinkVector::iterator I = Links.begin(), E = Links.end(); I != E; ++I) {
-      if (nodes[I->second].Value == -1)
-        SumN += I->first;
-      else if (nodes[I->second].Value == 1)
-        SumP += I->first;
+    for (std::pair<BlockFrequency, unsigned> &L : Links) {
+      if (nodes[L.second].Value == -1)
+        SumN += L.first;
+      else if (nodes[L.second].Value == 1)
+        SumP += L.first;
     }
 
     // Each weighted sum is going to be less than the total frequency of the
@@ -258,35 +258,33 @@ void SpillPlacement::setThreshold(const BlockFrequency &Entry) {
 /// addConstraints - Compute node biases and weights from a set of constraints.
 /// Set a bit in NodeMask for each active node.
 void SpillPlacement::addConstraints(ArrayRef<BlockConstraint> LiveBlocks) {
-  for (ArrayRef<BlockConstraint>::iterator I = LiveBlocks.begin(),
-       E = LiveBlocks.end(); I != E; ++I) {
-    BlockFrequency Freq = BlockFrequencies[I->Number];
+  for (const BlockConstraint &LB : LiveBlocks) {
+    BlockFrequency Freq = BlockFrequencies[LB.Number];
 
     // Live-in to block?
-    if (I->Entry != DontCare) {
-      unsigned ib = bundles->getBundle(I->Number, false);
+    if (LB.Entry != DontCare) {
+      unsigned ib = bundles->getBundle(LB.Number, false);
       activate(ib);
-      nodes[ib].addBias(Freq, I->Entry);
+      nodes[ib].addBias(Freq, LB.Entry);
     }
 
     // Live-out from block?
-    if (I->Exit != DontCare) {
-      unsigned ob = bundles->getBundle(I->Number, true);
+    if (LB.Exit != DontCare) {
+      unsigned ob = bundles->getBundle(LB.Number, true);
       activate(ob);
-      nodes[ob].addBias(Freq, I->Exit);
+      nodes[ob].addBias(Freq, LB.Exit);
     }
   }
 }
 
 /// addPrefSpill - Same as addConstraints(PrefSpill)
 void SpillPlacement::addPrefSpill(ArrayRef<unsigned> Blocks, bool Strong) {
-  for (ArrayRef<unsigned>::iterator I = Blocks.begin(), E = Blocks.end();
-       I != E; ++I) {
-    BlockFrequency Freq = BlockFrequencies[*I];
+  for (unsigned B : Blocks) {
+    BlockFrequency Freq = BlockFrequencies[B];
     if (Strong)
       Freq += Freq;
-    unsigned ib = bundles->getBundle(*I, false);
-    unsigned ob = bundles->getBundle(*I, true);
+    unsigned ib = bundles->getBundle(B, false);
+    unsigned ob = bundles->getBundle(B, true);
     activate(ib);
     activate(ob);
     nodes[ib].addBias(Freq, PrefSpill);
@@ -295,9 +293,7 @@ void SpillPlacement::addPrefSpill(ArrayRef<unsigned> Blocks, bool Strong) {
 }
 
 void SpillPlacement::addLinks(ArrayRef<unsigned> Links) {
-  for (ArrayRef<unsigned>::iterator I = Links.begin(), E = Links.end(); I != E;
-       ++I) {
-    unsigned Number = *I;
+  for (unsigned Number : Links) {
     unsigned ib = bundles->getBundle(Number, false);
     unsigned ob = bundles->getBundle(Number, true);
 
diff --git a/lib/CodeGen/SplitKit.cpp b/lib/CodeGen/SplitKit.cpp
index 5f97729bd9d..d3e75ca6001 100644
--- a/lib/CodeGen/SplitKit.cpp
+++ b/lib/CodeGen/SplitKit.cpp
@@ -1364,8 +1364,8 @@ void SplitEditor::rewriteAssigned(bool ExtendRanges) {
 
 void SplitEditor::deleteRematVictims() {
   SmallVector<MachineInstr*, 8> Dead;
-  for (LiveRangeEdit::iterator I = Edit->begin(), E = Edit->end(); I != E; ++I){
-    LiveInterval *LI = &LIS.getInterval(*I);
+  for (const Register &R : *Edit) {
+    LiveInterval *LI = &LIS.getInterval(R);
     for (const LiveRange::Segment &S : LI->segments) {
       // Dead defs end at the dead slot.
       if (S.end != S.valno->def.getDeadSlot())
diff --git a/lib/CodeGen/StackSlotColoring.cpp b/lib/CodeGen/StackSlotColoring.cpp
index a6f8974f334..bd5653f63a6 100644
--- a/lib/CodeGen/StackSlotColoring.cpp
+++ b/lib/CodeGen/StackSlotColoring.cpp
@@ -157,12 +157,8 @@ void StackSlotColoring::ScanForSpillSlotRefs(MachineFunction &MF) {
   SSRefs.resize(MFI->getObjectIndexEnd());
 
   // FIXME: Need the equivalent of MachineRegisterInfo for frameindex operands.
-  for (MachineFunction::iterator MBBI = MF.begin(), E = MF.end();
-       MBBI != E; ++MBBI) {
-    MachineBasicBlock *MBB = &*MBBI;
-    for (MachineBasicBlock::iterator MII = MBB->begin(), EE = MBB->end();
-         MII != EE; ++MII) {
-      MachineInstr &MI = *MII;
+  for (MachineBasicBlock &MBB : MF) {
+    for (MachineInstr &MI : MBB) {
       for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
         MachineOperand &MO = MI.getOperand(i);
         if (!MO.isFI())
@@ -474,9 +470,8 @@ bool StackSlotColoring::RemoveDeadStores(MachineBasicBlock* MBB) {
     ++I;
   }
 
-  for (SmallVectorImpl<MachineInstr *>::iterator I = toErase.begin(),
-       E = toErase.end(); I != E; ++I)
-    (*I)->eraseFromParent();
+  for (MachineInstr *MI : toErase)
+    MI->eraseFromParent();
 
   return changed;
 }
diff --git a/lib/CodeGen/TwoAddressInstructionPass.cpp b/lib/CodeGen/TwoAddressInstructionPass.cpp
index 2a9132bd2fe..a011b03d747 100644
--- a/lib/CodeGen/TwoAddressInstructionPass.cpp
+++ b/lib/CodeGen/TwoAddressInstructionPass.cpp
@@ -1549,9 +1549,8 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &Func) {
       .set(MachineFunctionProperties::Property::TiedOpsRewritten);
 
   TiedOperandMap TiedOperands;
-  for (MachineFunction::iterator MBBI = MF->begin(), MBBE = MF->end();
-       MBBI != MBBE; ++MBBI) {
-    MBB = &*MBBI;
+  for (MachineBasicBlock &MBBI : *MF) {
+    MBB = &MBBI;
     unsigned Dist = 0;
     DistanceMap.clear();
     SrcRegMap.clear();