diff --git a/llvm/lib/CodeGen/CriticalAntiDepBreaker.cpp b/llvm/lib/CodeGen/CriticalAntiDepBreaker.cpp
index 4144c243a3414..4a4a2785d51e4 100644
--- a/llvm/lib/CodeGen/CriticalAntiDepBreaker.cpp
+++ b/llvm/lib/CodeGen/CriticalAntiDepBreaker.cpp
@@ -261,15 +261,25 @@ void CriticalAntiDepBreaker::ScanInstruction(MachineInstr &MI, unsigned Count) {
     for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
       MachineOperand &MO = MI.getOperand(i);
 
-      if (MO.isRegMask())
-        for (unsigned i = 0, e = TRI->getNumRegs(); i != e; ++i)
-          if (MO.clobbersPhysReg(i)) {
+      if (MO.isRegMask()) {
+        auto ClobbersPhysRegAndSubRegs = [&](unsigned PhysReg) {
+          for (MCSubRegIterator SRI(PhysReg, TRI, true); SRI.isValid(); ++SRI)
+            if (!MO.clobbersPhysReg(*SRI))
+              return false;
+
+          return true;
+        };
+
+        for (unsigned i = 0, e = TRI->getNumRegs(); i != e; ++i) {
+          if (ClobbersPhysRegAndSubRegs(i)) {
             DefIndices[i] = Count;
             KillIndices[i] = ~0u;
             KeepRegs.reset(i);
             Classes[i] = nullptr;
             RegRefs.erase(i);
           }
+        }
+      }
 
       if (!MO.isReg()) continue;
       unsigned Reg = MO.getReg();