diff --git a/llvm/include/llvm/CodeGen/RegisterScavenging.h b/llvm/include/llvm/CodeGen/RegisterScavenging.h
--- a/llvm/include/llvm/CodeGen/RegisterScavenging.h
+++ b/llvm/include/llvm/CodeGen/RegisterScavenging.h
@@ -194,10 +194,10 @@
   void determineKillsAndDefs();
 
   /// Add all Reg Units that Reg contains to BV.
-  void addRegUnits(BitVector &BV, Register Reg);
+  void addRegUnits(BitVector &BV, MCRegister Reg);
 
   /// Remove all Reg Units that \p Reg contains from \p BV.
-  void removeRegUnits(BitVector &BV, Register Reg);
+  void removeRegUnits(BitVector &BV, MCRegister Reg);
 
   /// Return the candidate register that is unused for the longest after
   /// StartMI. UseMI is set to the instruction where the search stopped.
diff --git a/llvm/lib/CodeGen/RegAllocBasic.cpp b/llvm/lib/CodeGen/RegAllocBasic.cpp
--- a/llvm/lib/CodeGen/RegAllocBasic.cpp
+++ b/llvm/lib/CodeGen/RegAllocBasic.cpp
@@ -119,7 +119,7 @@
   // Helper for spilling all live virtual registers currently unified under preg
   // that interfere with the most recently queried lvr.  Return true if spilling
   // was successful, and append any new spilled/split intervals to splitLVRs.
-  bool spillInterferences(LiveInterval &VirtReg, Register PhysReg,
+  bool spillInterferences(LiveInterval &VirtReg, MCRegister PhysReg,
                           SmallVectorImpl<Register> &SplitVRegs);
 
   static char ID;
@@ -206,7 +206,7 @@
 // Spill or split all live virtual registers currently unified under PhysReg
 // that interfere with VirtReg. The newly spilled or split live intervals are
 // returned by appending them to SplitVRegs.
-bool RABasic::spillInterferences(LiveInterval &VirtReg, Register PhysReg,
+bool RABasic::spillInterferences(LiveInterval &VirtReg, MCRegister PhysReg,
                                  SmallVectorImpl<Register> &SplitVRegs) {
   // Record each interference and determine if all are spillable before mutating
   // either the union or live intervals.
diff --git a/llvm/lib/CodeGen/RegAllocFast.cpp b/llvm/lib/CodeGen/RegAllocFast.cpp
--- a/llvm/lib/CodeGen/RegAllocFast.cpp
+++ b/llvm/lib/CodeGen/RegAllocFast.cpp
@@ -495,7 +495,7 @@
     if (PhysReg == 0)
       continue;
 
-    unsigned FirstUnit = *MCRegUnitIterator(PhysReg, TRI);
+    MCRegister FirstUnit = *MCRegUnitIterator(PhysReg, TRI);
     if (RegUnitStates[FirstUnit] == regLiveIn)
       continue;
 
@@ -566,7 +566,7 @@
 void RegAllocFast::freePhysReg(MCPhysReg PhysReg) {
   LLVM_DEBUG(dbgs() << "Freeing " << printReg(PhysReg, TRI) << ':');
 
-  unsigned FirstUnit = *MCRegUnitIterator(PhysReg, TRI);
+  MCRegister FirstUnit = *MCRegUnitIterator(PhysReg, TRI);
   switch (unsigned VirtReg = RegUnitStates[FirstUnit]) {
   case regFree:
     LLVM_DEBUG(dbgs() << '\n');
diff --git a/llvm/lib/CodeGen/RegisterScavenging.cpp b/llvm/lib/CodeGen/RegisterScavenging.cpp
--- a/llvm/lib/CodeGen/RegisterScavenging.cpp
+++ b/llvm/lib/CodeGen/RegisterScavenging.cpp
@@ -97,12 +97,12 @@
   }
 }
 
-void RegScavenger::addRegUnits(BitVector &BV, Register Reg) {
+void RegScavenger::addRegUnits(BitVector &BV, MCRegister Reg) {
   for (MCRegUnitIterator RUI(Reg, TRI); RUI.isValid(); ++RUI)
     BV.set(*RUI);
 }
 
-void RegScavenger::removeRegUnits(BitVector &BV, Register Reg) {
+void RegScavenger::removeRegUnits(BitVector &BV, MCRegister Reg) {
   for (MCRegUnitIterator RUI(Reg, TRI); RUI.isValid(); ++RUI)
     BV.reset(*RUI);
 }
@@ -134,9 +134,9 @@
     }
     if (!MO.isReg())
       continue;
-    Register Reg = MO.getReg();
-    if (!Register::isPhysicalRegister(Reg) || isReserved(Reg))
+    if (!MO.getReg().isPhysical() || isReserved(MO.getReg()))
       continue;
+    MCRegister Reg = MO.getReg().asMCReg();
 
     if (MO.isUse()) {
       // Ignore undef uses.
diff --git a/llvm/lib/CodeGen/VirtRegMap.cpp b/llvm/lib/CodeGen/VirtRegMap.cpp
--- a/llvm/lib/CodeGen/VirtRegMap.cpp
+++ b/llvm/lib/CodeGen/VirtRegMap.cpp
@@ -187,7 +187,7 @@
   void addLiveInsForSubRanges(const LiveInterval &LI, Register PhysReg) const;
   void handleIdentityCopy(MachineInstr &MI) const;
   void expandCopyBundle(MachineInstr &MI) const;
-  bool subRegLiveThrough(const MachineInstr &MI, Register SuperPhysReg) const;
+  bool subRegLiveThrough(const MachineInstr &MI, MCRegister SuperPhysReg) const;
 
 public:
   static char ID;
@@ -468,7 +468,7 @@
 /// \pre \p MI defines a subregister of a virtual register that
 /// has been assigned to \p SuperPhysReg.
 bool VirtRegRewriter::subRegLiveThrough(const MachineInstr &MI,
-                                        Register SuperPhysReg) const {
+                                        MCRegister SuperPhysReg) const {
   SlotIndex MIIndex = LIS->getInstructionIndex(MI);
   SlotIndex BeforeMIUses = MIIndex.getBaseIndex();
   SlotIndex AfterMIDefs = MIIndex.getBoundaryIndex();
@@ -515,7 +515,7 @@
         if (!MO.isReg() || !MO.getReg().isVirtual())
           continue;
         Register VirtReg = MO.getReg();
-        Register PhysReg = VRM->getPhys(VirtReg);
+        MCRegister PhysReg = VRM->getPhys(VirtReg);
         assert(PhysReg != VirtRegMap::NO_PHYS_REG &&
                "Instruction uses unmapped VirtReg");
         assert(!MRI->isReserved(PhysReg) && "Reserved register assignment");