Index: lib/CodeGen/MachineBlockPlacement.cpp
===================================================================
--- lib/CodeGen/MachineBlockPlacement.cpp
+++ lib/CodeGen/MachineBlockPlacement.cpp
@@ -1491,8 +1491,13 @@
   assert(LoopChain.UnscheduledPredecessors == 0);
   UpdatedPreds.insert(&LoopChain);
 
-  for (MachineBasicBlock *LoopBB : LoopBlockSet)
-    fillWorkLists(LoopBB, UpdatedPreds, &LoopBlockSet);
+   // Add the basic blocks to LoopBlockSet. Note that we are NOT using the
+   // LoopBlockSet iterator here because its order depends on the pointer
+   // values. This nondeterministic order will fail to produce a bit-to-bit
+   // matching clang binary in bootstrap build.
+   for (MachineBasicBlock &LoopBB : *F)
+     if (LoopBlockSet.count(&LoopBB))
+       fillWorkLists(&LoopBB, UpdatedPreds, &LoopBlockSet);
 
   buildChain(LoopTop, LoopChain, &LoopBlockSet);