diff --git a/include/llvm/CodeGen/LiveRegUnits.h b/include/llvm/CodeGen/LiveRegUnits.h
index c7b811d..0c6df88 100644
--- a/include/llvm/CodeGen/LiveRegUnits.h
+++ b/include/llvm/CodeGen/LiveRegUnits.h
@@ -32,47 +32,30 @@
   SmallSet<unsigned, 32> LiveUnits;
 
 public:
-  /// Constructs a new empty LiveRegUnits set.
-  LiveRegUnits() {
-  }
+  /// \brief Constructs a new empty LiveRegUnits set.
+  LiveRegUnits() {}
 
-  /// Constructs a new LiveRegUnits set by copying @p Other.
+  /// \brief Constructs a new LiveRegUnits set by copying @p Other.
   LiveRegUnits(const LiveRegUnits &Other)
     : LiveUnits(Other.LiveUnits) {
   }
 
-  /// Adds a register to the set.
+  /// \brief Adds a register to the set.
   void addReg(unsigned Reg, const MCRegisterInfo &MCRI) {
     for (MCRegUnitIterator RUnits(Reg, &MCRI); RUnits.isValid(); ++RUnits)
       LiveUnits.insert(*RUnits);
   }
 
-  /// Removes a register from the set.
+  /// \brief Removes a register from the set.
   void removeReg(unsigned Reg, const MCRegisterInfo &MCRI) {
     for (MCRegUnitIterator RUnits(Reg, &MCRI); RUnits.isValid(); ++RUnits)
       LiveUnits.erase(*RUnits);
   }
 
   /// \brief Removes registers clobbered by the regmask operand @p Op.
-  /// Note that we assume the high bits of a physical super register are not
-  /// preserved unless the instruction has an implicit-use operand reading
-  /// the super-register or a register unit for the upper bits is available.
-  void removeRegsInMask(const MachineOperand &Op,
-                        const MCRegisterInfo &MCRI) {
-    const uint32_t *Mask = Op.getRegMask();
-    unsigned Bit = 0;
-    for (unsigned R = 0; R < MCRI.getNumRegs(); ++R) {
-      if ((*Mask & (1u << Bit)) == 0)
-        removeReg(R, MCRI);
-      ++Bit;
-      if (Bit >= 32) {
-        Bit = 0;
-        ++Mask;
-      }
-    }
-  }
+  void removeRegsInMask(const MachineOperand &Op, const MCRegisterInfo &MCRI);
 
-  /// Returns true if register @p Reg (or one of its super register) is
+  /// \brief Returns true if register @p Reg (or one of its super register) is
   /// contained in the set.
   bool contains(unsigned Reg, const MCRegisterInfo &MCRI) const {
     for (MCRegUnitIterator RUnits(Reg, &MCRI); RUnits.isValid(); ++RUnits) {
@@ -82,73 +65,16 @@
     return false;
   }
 
-  /// Simulates liveness when stepping backwards over an instruction(bundle):
-  /// Defs are removed from the set, uses added.
-  void stepBackward(const MachineInstr &MI, const MCRegisterInfo &MCRI) {
-    // Remove defined registers and regmask kills from the set.
-    for (ConstMIBundleOperands O(&MI); O.isValid(); ++O) {
-      if (O->isReg()) {
-        if (!O->isDef())
-          continue;
-        unsigned Reg = O->getReg();
-        if (Reg == 0)
-          continue;
-        removeReg(Reg, MCRI);
-      } else if (O->isRegMask()) {
-        removeRegsInMask(*O, MCRI);
-      }
-    }
-    // Add uses to the set.
-    for (ConstMIBundleOperands O(&MI); O.isValid(); ++O) {
-      if (!O->isReg() || !O->readsReg() || O->isUndef())
-        continue;
-      unsigned Reg = O->getReg();
-      if (Reg == 0)
-        continue;
-      addReg(Reg, MCRI);
-    }
-  }
+  /// \brief Simulates liveness when stepping backwards over an
+  /// instruction(bundle): Remove Defs, add uses.
+  void stepBackward(const MachineInstr &MI, const MCRegisterInfo &MCRI);
 
   /// \brief Simulates liveness when stepping forward over an
-  /// instruction(bundle).
-  ///
-  /// Uses with kill flag get removed from the set, defs added. If possible
-  /// use StepBackward() instead of this function because some kill flags may
-  /// be missing.
-  void stepForward(const MachineInstr &MI, const MCRegisterInfo &MCRI) {
-    SmallVector<unsigned, 4> Defs;
-    // Remove killed registers from the set.
-    for (ConstMIBundleOperands O(&MI); O.isValid(); ++O) {
-      if (O->isReg()) {
-        unsigned Reg = O->getReg();
-        if (Reg == 0)
-          continue;
-        if (O->isDef()) {
-          if (!O->isDead())
-            Defs.push_back(Reg);
-        } else {
-          if (!O->isKill())
-            continue;
-          assert(O->isUse());
-          removeReg(Reg, MCRI);
-        }
-      } else if (O->isRegMask()) {
-        removeRegsInMask(*O, MCRI);
-      }
-    }
-    // Add defs to the set.
-    for (unsigned i = 0, e = Defs.size(); i != e; ++i) {
-      addReg(Defs[i], MCRI);
-    }
-  }
+  /// instruction(bundle): Remove killed-uses, add defs.
+  void stepForward(const MachineInstr &MI, const MCRegisterInfo &MCRI);
 
   /// Adds all registers in the live-in list of block @p BB.
-  void addLiveIns(const MachineBasicBlock &BB, const MCRegisterInfo &MCRI) {
-    for (MachineBasicBlock::livein_iterator L = BB.livein_begin(),
-         LE = BB.livein_end(); L != LE; ++L) {
-      addReg(*L, MCRI);
-    }
-  }
+  void addLiveIns(const MachineBasicBlock &BB, const MCRegisterInfo &MCRI);
 };
 
 } // namespace llvm
diff --git a/lib/CodeGen/CMakeLists.txt b/lib/CodeGen/CMakeLists.txt
index a00df3b..5aa5a75 100644
--- a/lib/CodeGen/CMakeLists.txt
+++ b/lib/CodeGen/CMakeLists.txt
@@ -35,6 +35,7 @@
   LiveRangeCalc.cpp
   LiveRangeEdit.cpp
   LiveRegMatrix.cpp
+  LiveRegUnits.cpp
   LiveStackAnalysis.cpp
   LiveVariables.cpp
   LocalStackSlotAllocation.cpp
diff --git a/lib/CodeGen/LiveRegUnits.cpp b/lib/CodeGen/LiveRegUnits.cpp
new file mode 100644
index 0000000..c9fa40e
--- /dev/null
+++ b/lib/CodeGen/LiveRegUnits.cpp
@@ -0,0 +1,102 @@
+//===-- LiveInterval.cpp - Live Interval Representation -------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the LiveRegUnits utility for tracking liveness of
+// physical register units across machine instructions in forward or backward
+// order.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/LiveRegUnits.h"
+#include "llvm/CodeGen/MachineInstrBundle.h"
+using namespace llvm;
+
+/// We assume the high bits of a physical super register are not preserved
+/// unless the instruction has an implicit-use operand reading the
+/// super-register or a register unit for the upper bits is available.
+void LiveRegUnits::removeRegsInMask(const MachineOperand &Op,
+                                    const MCRegisterInfo &MCRI) {
+  const uint32_t *Mask = Op.getRegMask();
+  unsigned Bit = 0;
+  for (unsigned R = 0; R < MCRI.getNumRegs(); ++R) {
+    if ((*Mask & (1u << Bit)) == 0)
+      removeReg(R, MCRI);
+    ++Bit;
+    if (Bit >= 32) {
+      Bit = 0;
+      ++Mask;
+    }
+  }
+}
+
+void LiveRegUnits::stepBackward(const MachineInstr &MI,
+                                const MCRegisterInfo &MCRI) {
+  // Remove defined registers and regmask kills from the set.
+  for (ConstMIBundleOperands O(&MI); O.isValid(); ++O) {
+    if (O->isReg()) {
+      if (!O->isDef())
+        continue;
+      unsigned Reg = O->getReg();
+      if (Reg == 0)
+        continue;
+      removeReg(Reg, MCRI);
+    } else if (O->isRegMask()) {
+      removeRegsInMask(*O, MCRI);
+    }
+  }
+  // Add uses to the set.
+  for (ConstMIBundleOperands O(&MI); O.isValid(); ++O) {
+    if (!O->isReg() || !O->readsReg() || O->isUndef())
+      continue;
+    unsigned Reg = O->getReg();
+    if (Reg == 0)
+      continue;
+    addReg(Reg, MCRI);
+  }
+}
+
+/// Uses with kill flag get removed from the set, defs added. If possible
+/// use StepBackward() instead of this function because some kill flags may
+/// be missing.
+void LiveRegUnits::stepForward(const MachineInstr &MI,
+                               const MCRegisterInfo &MCRI) {
+  SmallVector<unsigned, 4> Defs;
+  // Remove killed registers from the set.
+  for (ConstMIBundleOperands O(&MI); O.isValid(); ++O) {
+    if (O->isReg()) {
+      unsigned Reg = O->getReg();
+      if (Reg == 0)
+        continue;
+      if (O->isDef()) {
+        if (!O->isDead())
+          Defs.push_back(Reg);
+      } else {
+        if (!O->isKill())
+          continue;
+        assert(O->isUse());
+        removeReg(Reg, MCRI);
+      }
+    } else if (O->isRegMask()) {
+      removeRegsInMask(*O, MCRI);
+    }
+  }
+  // Add defs to the set.
+  for (unsigned i = 0, e = Defs.size(); i != e; ++i) {
+    addReg(Defs[i], MCRI);
+  }
+}
+
+/// Adds all registers in the live-in list of block @p BB.
+void LiveRegUnits::addLiveIns(const MachineBasicBlock &BB,
+                              const MCRegisterInfo &MCRI) {
+  for (MachineBasicBlock::livein_iterator L = BB.livein_begin(),
+       LE = BB.livein_end(); L != LE; ++L) {
+    addReg(*L, MCRI);
+  }
+}