diff --git a/lib/CodeGen/MachineLoopInfo.cpp b/lib/CodeGen/MachineLoopInfo.cpp
index b5d5ad9..b7298e4 100644
--- a/lib/CodeGen/MachineLoopInfo.cpp
+++ b/lib/CodeGen/MachineLoopInfo.cpp
@@ -18,6 +18,7 @@
 #include "llvm/CodeGen/MachineDominators.h"
 #include "llvm/CodeGen/Passes.h"
 #include "llvm/Analysis/LoopInfoImpl.h"
+#include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 using namespace llvm;
 
@@ -25,6 +26,10 @@
 template class llvm::LoopBase<MachineBasicBlock, MachineLoop>;
 template class llvm::LoopInfoBase<MachineBasicBlock, MachineLoop>;
 
+static cl::opt<bool>
+StableLoopInfo("stable-machine-loops", cl::Hidden, cl::init(false),
+               cl::desc("Compute a stable loop tree."));
+
 char MachineLoopInfo::ID = 0;
 INITIALIZE_PASS_BEGIN(MachineLoopInfo, "machine-loops",
                 "Machine Natural Loop Construction", true, true)
@@ -36,7 +41,10 @@
 
 bool MachineLoopInfo::runOnMachineFunction(MachineFunction &) {
   releaseMemory();
-  LI.Calculate(getAnalysis<MachineDominatorTree>().getBase());    // Update
+  if (StableLoopInfo)
+    LI.Analyze(getAnalysis<MachineDominatorTree>().getBase());
+  else
+    LI.Calculate(getAnalysis<MachineDominatorTree>().getBase());    // Update
   return false;
 }