diff --git a/lib/Target/ARM/Thumb2ITBlockPass.cpp b/lib/Target/ARM/Thumb2ITBlockPass.cpp
index ecb4c2f0e5d..e2166ffc322 100644
--- a/lib/Target/ARM/Thumb2ITBlockPass.cpp
+++ b/lib/Target/ARM/Thumb2ITBlockPass.cpp
@@ -15,6 +15,7 @@
 #include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/CodeGen/MachineInstrBundle.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/Statistic.h"
 using namespace llvm;
@@ -258,6 +259,9 @@ bool Thumb2ITBlockPass::runOnMachineFunction(MachineFunction &Fn) {
   if (!AFI->isThumbFunction())
     return false;
 
+  // IT block insertion invalidates accurate register liveness.
+  Fn.getRegInfo().invalidateLiveness();
+
   bool Modified = false;
   for (MachineFunction::iterator MFI = Fn.begin(), E = Fn.end(); MFI != E; ) {
     MachineBasicBlock &MBB = *MFI;