Index: include/llvm/Target/TargetRegisterInfo.h
===================================================================
--- include/llvm/Target/TargetRegisterInfo.h
+++ include/llvm/Target/TargetRegisterInfo.h
@@ -674,6 +674,15 @@
     return 0;
   }
 
+  /// Return a heuristic for the machine scheduler to compare the profitability
+  /// of increasing one register pressure set versus another.  The scheduler
+  /// will prefer increasing the register pressure of the set which returns
+  /// the largest value for this function.
+  virtual unsigned getRegPressureSetScore(const MachineFunction &MF,
+                                          unsigned PSetID) const {
+    return PSetID;
+  }
+
   /// Get the weight in units of pressure for this register class.
   virtual const RegClassWeight &getRegClassWeight(
     const TargetRegisterClass *RC) const = 0;
Index: lib/CodeGen/MachineScheduler.cpp
===================================================================
--- lib/CodeGen/MachineScheduler.cpp
+++ lib/CodeGen/MachineScheduler.cpp
@@ -2579,7 +2579,9 @@
                         const PressureChange &CandP,
                         GenericSchedulerBase::SchedCandidate &TryCand,
                         GenericSchedulerBase::SchedCandidate &Cand,
-                        GenericSchedulerBase::CandReason Reason) {
+                        GenericSchedulerBase::CandReason Reason,
+                        const TargetRegisterInfo *TRI,
+                        const MachineFunction &MF) {
   int TryRank = TryP.getPSetOrMax();
   int CandRank = CandP.getPSetOrMax();
   // If both candidates affect the same set, go with the smallest increase.
@@ -2593,6 +2595,12 @@
                  Reason)) {
     return true;
   }
+
+  if (TryP.isValid())
+    TryRank = TRI->getRegPressureSetScore(MF, TryRank);
+  if (CandP.isValid())
+    CandRank =TRI->getRegPressureSetScore(MF, CandRank);
+
   // If the candidates are decreasing pressure, reverse priority.
   if (TryP.getUnitInc() < 0)
     std::swap(TryRank, CandRank);
@@ -2695,13 +2703,15 @@
   // Avoid exceeding the target's limit.
   if (DAG->isTrackingPressure() && tryPressure(TryCand.RPDelta.Excess,
                                                Cand.RPDelta.Excess,
-                                               TryCand, Cand, RegExcess))
+                                               TryCand, Cand, RegExcess, TRI,
+                                               DAG->MF))
     return;
 
   // Avoid increasing the max critical pressure in the scheduled region.
   if (DAG->isTrackingPressure() && tryPressure(TryCand.RPDelta.CriticalMax,
                                                Cand.RPDelta.CriticalMax,
-                                               TryCand, Cand, RegCritical))
+                                               TryCand, Cand, RegCritical, TRI,
+                                               DAG->MF))
     return;
 
   // For loops that are acyclic path limited, aggressively schedule for latency.
@@ -2737,7 +2747,8 @@
   // Avoid increasing the max pressure of the entire region.
   if (DAG->isTrackingPressure() && tryPressure(TryCand.RPDelta.CurrentMax,
                                                Cand.RPDelta.CurrentMax,
-                                               TryCand, Cand, RegMax))
+                                               TryCand, Cand, RegMax, TRI,
+                                               DAG->MF))
     return;
 
   // Avoid critical resource consumption and balance the schedule.