diff --git a/lib/CodeGen/MachineScheduler.cpp b/lib/CodeGen/MachineScheduler.cpp
index cc7aabd..0789a74 100644
--- a/lib/CodeGen/MachineScheduler.cpp
+++ b/lib/CodeGen/MachineScheduler.cpp
@@ -603,7 +603,11 @@
 
   SchedImpl->registerRoots();
 
+  // Advance past initial DebugValues.
+  assert(TopRPTracker.getPos() == RegionBegin && "bad initial Top tracker");
   CurrentTop = nextIfDebug(RegionBegin, RegionEnd);
+  TopRPTracker.setPos(CurrentTop);
+
   CurrentBottom = RegionEnd;
 }