diff --git a/lib/CodeGen/SpillPlacement.cpp b/lib/CodeGen/SpillPlacement.cpp
index 69496186326..ce7b37bfce5 100644
--- a/lib/CodeGen/SpillPlacement.cpp
+++ b/lib/CodeGen/SpillPlacement.cpp
@@ -239,6 +239,20 @@ void SpillPlacement::addConstraints(ArrayRef<BlockConstraint> LiveBlocks) {
   }
 }
 
+/// addPrefSpill - Same as addConstraints(PrefSpill)
+void SpillPlacement::addPrefSpill(ArrayRef<unsigned> Blocks) {
+  for (ArrayRef<unsigned>::iterator I = Blocks.begin(), E = Blocks.end();
+       I != E; ++I) {
+    float Freq = getBlockFrequency(*I);
+    unsigned ib = bundles->getBundle(*I, 0);
+    unsigned ob = bundles->getBundle(*I, 1);
+    activate(ib);
+    activate(ob);
+    nodes[ib].addBias(-Freq, 1);
+    nodes[ob].addBias(-Freq, 0);
+  }
+}
+
 void SpillPlacement::addLinks(ArrayRef<unsigned> Links) {
   for (ArrayRef<unsigned>::iterator I = Links.begin(), E = Links.end(); I != E;
        ++I) {
diff --git a/lib/CodeGen/SpillPlacement.h b/lib/CodeGen/SpillPlacement.h
index 6952ad80096..9a4fc6dc970 100644
--- a/lib/CodeGen/SpillPlacement.h
+++ b/lib/CodeGen/SpillPlacement.h
@@ -96,6 +96,10 @@ public:
   ///                   live out.
   void addConstraints(ArrayRef<BlockConstraint> LiveBlocks);
 
+  /// addPrefSpill - Add PrefSpill constraints to all blocks listed.
+  /// @param Blocks Array of block numbers that prefer to spill in and out.
+  void addPrefSpill(ArrayRef<unsigned> Blocks);
+
   /// addLinks - Add transparent blocks with the given numbers.
   void addLinks(ArrayRef<unsigned> Links);