diff --git a/llvm/include/llvm/CodeGen/MachineBasicBlock.h b/llvm/include/llvm/CodeGen/MachineBasicBlock.h
index 1183ebbec944..8aac7b1fd13b 100644
--- a/llvm/include/llvm/CodeGen/MachineBasicBlock.h
+++ b/llvm/include/llvm/CodeGen/MachineBasicBlock.h
@@ -16,6 +16,7 @@
 
 #include "llvm/ADT/GraphTraits.h"
 #include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/MC/MCRegisterInfo.h"
 #include "llvm/Support/DataTypes.h"
 #include <functional>
 
@@ -79,7 +80,8 @@ class MachineBasicBlock : public ilist_node<MachineBasicBlock> {
   typedef std::vector<uint32_t>::const_iterator const_weight_iterator;
 
   /// Keep track of the physical registers that are livein of the basicblock.
-  std::vector<unsigned> LiveIns;
+  typedef std::vector<MCPhysReg> LiveInVector;
+  LiveInVector LiveIns;
 
   /// Alignment of the basic block. Zero if the basic block does not need to be
   /// aligned. The alignment is specified as log2(bytes).
@@ -309,7 +311,7 @@ public:
   /// Adds the specified register as a live in. Note that it is an error to add
   /// the same register to the same set more than once unless the intention is
   /// to call sortUniqueLiveIns after all registers are added.
-  void addLiveIn(unsigned Reg) { LiveIns.push_back(Reg); }
+  void addLiveIn(MCPhysReg PhysReg) { LiveIns.push_back(PhysReg); }
 
   /// Sorts and uniques the LiveIns vector. It can be significantly faster to do
   /// this than repeatedly calling isLiveIn before calling addLiveIn for every
@@ -322,17 +324,17 @@ public:
   /// Add PhysReg as live in to this block, and ensure that there is a copy of
   /// PhysReg to a virtual register of class RC. Return the virtual register
   /// that is a copy of the live in PhysReg.
-  unsigned addLiveIn(unsigned PhysReg, const TargetRegisterClass *RC);
+  unsigned addLiveIn(MCPhysReg PhysReg, const TargetRegisterClass *RC);
 
   /// Remove the specified register from the live in set.
-  void removeLiveIn(unsigned Reg);
+  void removeLiveIn(MCPhysReg Reg);
 
   /// Return true if the specified register is in the live in set.
-  bool isLiveIn(unsigned Reg) const;
+  bool isLiveIn(MCPhysReg Reg) const;
 
   // Iteration support for live in sets.  These sets are kept in sorted
   // order by their register number.
-  typedef std::vector<unsigned>::const_iterator livein_iterator;
+  typedef LiveInVector::const_iterator livein_iterator;
   livein_iterator livein_begin() const { return LiveIns.begin(); }
   livein_iterator livein_end()   const { return LiveIns.end(); }
   bool            livein_empty() const { return LiveIns.empty(); }
diff --git a/llvm/lib/CodeGen/MachineBasicBlock.cpp b/llvm/lib/CodeGen/MachineBasicBlock.cpp
index 9ff4858f0a4e..c30b95a6b2d6 100644
--- a/llvm/lib/CodeGen/MachineBasicBlock.cpp
+++ b/llvm/lib/CodeGen/MachineBasicBlock.cpp
@@ -322,20 +322,19 @@ void MachineBasicBlock::printAsOperand(raw_ostream &OS,
   OS << "BB#" << getNumber();
 }
 
-void MachineBasicBlock::removeLiveIn(unsigned Reg) {
-  std::vector<unsigned>::iterator I
-    = std::find(LiveIns.begin(), LiveIns.end(), Reg);
+void MachineBasicBlock::removeLiveIn(MCPhysReg Reg) {
+  LiveInVector::iterator I = std::find(LiveIns.begin(), LiveIns.end(), Reg);
   if (I != LiveIns.end())
     LiveIns.erase(I);
 }
 
-bool MachineBasicBlock::isLiveIn(unsigned Reg) const {
+bool MachineBasicBlock::isLiveIn(MCPhysReg Reg) const {
   livein_iterator I = std::find(livein_begin(), livein_end(), Reg);
   return I != livein_end();
 }
 
 unsigned
-MachineBasicBlock::addLiveIn(unsigned PhysReg, const TargetRegisterClass *RC) {
+MachineBasicBlock::addLiveIn(MCPhysReg PhysReg, const TargetRegisterClass *RC) {
   assert(getParent() && "MBB must be inserted in function");
   assert(TargetRegisterInfo::isPhysicalRegister(PhysReg) && "Expected physreg");
   assert(RC && "Register class is required");