diff --git a/llvm/include/llvm/CodeGen/MachinePipeliner.h b/llvm/include/llvm/CodeGen/MachinePipeliner.h
--- a/llvm/include/llvm/CodeGen/MachinePipeliner.h
+++ b/llvm/include/llvm/CodeGen/MachinePipeliner.h
@@ -334,20 +334,21 @@
   NodeSet(iterator S, iterator E) : Nodes(S, E), HasRecurrence(true) {
     Latency = 0;
     for (unsigned i = 0, e = Nodes.size(); i < e; ++i) {
-      DenseMap<SUnit *, unsigned> SuccSUnitLatency;
+      // The next node is either the next node in the list, or the backedge to
+      // the first node
+      SUnit *NextSUnit = ((i + 1) == e) ? Nodes[0] : Nodes[i + 1];
+
+      // Calculate the maximum latency to NextSUnit from Nodes[i]
+      unsigned SuccLatency = 0;
       for (const SDep &Succ : Nodes[i]->Succs) {
-        auto SuccSUnit = Succ.getSUnit();
-        if (!Nodes.count(SuccSUnit))
+        SUnit *SuccSUnit = Succ.getSUnit();
+        if (SuccSUnit->NodeNum != NextSUnit->NodeNum)
           continue;
         unsigned CurLatency = Succ.getLatency();
-        unsigned MaxLatency = 0;
-        if (SuccSUnitLatency.count(SuccSUnit))
-          MaxLatency = SuccSUnitLatency[SuccSUnit];
-        if (CurLatency > MaxLatency)
-          SuccSUnitLatency[SuccSUnit] = CurLatency;
+        if (CurLatency > SuccLatency)
+          SuccLatency = CurLatency;
       }
-      for (auto SUnitLatency : SuccSUnitLatency)
-        Latency += SUnitLatency.second;
+      Latency += SuccLatency;
     }
   }