diff --git a/include/llvm/CodeGen/MachineScheduler.h b/include/llvm/CodeGen/MachineScheduler.h
index 2e39161d11..57febe7746 100644
--- a/include/llvm/CodeGen/MachineScheduler.h
+++ b/include/llvm/CodeGen/MachineScheduler.h
@@ -360,7 +360,7 @@ class ScheduleDAGMI : public ScheduleDAGInstrs {
 
   void initRegPressure();
 
-  void updateScheduledPressure(std::vector<unsigned> NewMaxPressure);
+  void updateScheduledPressure(const std::vector<unsigned> &NewMaxPressure);
 
   void moveInstruction(MachineInstr *MI, MachineBasicBlock::iterator InsertPos);
   bool checkSchedLimit();
diff --git a/lib/CodeGen/MachineScheduler.cpp b/lib/CodeGen/MachineScheduler.cpp
index ddaf56627b..589fa1fa02 100644
--- a/lib/CodeGen/MachineScheduler.cpp
+++ b/lib/CodeGen/MachineScheduler.cpp
@@ -487,7 +487,7 @@ void ScheduleDAGMI::initRegPressure() {
 // FIXME: When the pressure tracker deals in pressure differences then we won't
 // iterate over all RegionCriticalPSets[i].
 void ScheduleDAGMI::
-updateScheduledPressure(std::vector<unsigned> NewMaxPressure) {
+updateScheduledPressure(const std::vector<unsigned> &NewMaxPressure) {
   for (unsigned i = 0, e = RegionCriticalPSets.size(); i < e; ++i) {
     unsigned ID = RegionCriticalPSets[i].PSetID;
     int &MaxUnits = RegionCriticalPSets[i].UnitIncrease;