diff --git a/lib/CodeGen/IfConversion.cpp b/lib/CodeGen/IfConversion.cpp
index 938c9cf6039..4bad70925d7 100644
--- a/lib/CodeGen/IfConversion.cpp
+++ b/lib/CodeGen/IfConversion.cpp
@@ -985,6 +985,20 @@ static void UpdatePredRedefs(MachineInstr *MI, LivePhysRegs &Redefs) {
     // take a mutable instruction instead of const.
     MachineInstr *OpMI = const_cast<MachineInstr*>(Op.getParent());
     MachineInstrBuilder MIB(*OpMI->getParent()->getParent(), OpMI);
+
+    if (Op.isRegMask()) {
+      // First handle regmasks.  They clobber any entries in the mask which
+      // means that we need a def for those registers.
+      MIB.addReg(Reg.first, RegState::Implicit | RegState::Undef);
+
+      // We also need to add an implicit def of this register for the later
+      // use to read from.
+      // For the register allocator to have allocated a register clobbered
+      // by the call which is used later, it must be the case that
+      // the call doesn't return.
+      MIB.addReg(Reg.first, RegState::Implicit | RegState::Define);
+      continue;
+    }
     assert(Op.isReg() && "Register operand required");
     MIB.addReg(Reg.first, RegState::Implicit | RegState::Undef);
   }
diff --git a/test/CodeGen/ARM/ifcvt-regmask-noreturn.ll b/test/CodeGen/ARM/ifcvt-regmask-noreturn.ll
new file mode 100644
index 00000000000..cf04fc90504
--- /dev/null
+++ b/test/CodeGen/ARM/ifcvt-regmask-noreturn.ll
@@ -0,0 +1,45 @@
+; RUN: llc %s -o - -verify-machineinstrs | FileCheck %s
+
+target datalayout = "e-m:o-p:32:32-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32"
+target triple = "thumbv7s-apple-ios8.0.0"
+
+@debw = external global i8*, align 4
+
+; This test ensures that the stack_chk call correctly puts implicit uses/defs for the regsiters
+; live across it when if converting.  This will be R0 which is passed to the call to free at the end
+; of the function.
+; Prior to this change, the stack_chk call (which does not return) would clobber R0 in its regmask,
+; leading to verifier errors because the later use of R0 in free() is not live.
+
+; CHECK-LABEL: @test
+; CHECK: stack_chk_fail
+
+; Function Attrs: ssp
+define void @test(i32 %argc, i8** nocapture readonly %argv, i32* %ptr, i32 %val) #0 {
+entry:
+  %count.i = alloca [256 x i32], align 4
+  %cmp284.i = icmp eq i32 %val, 0
+  br i1 %cmp284.i, label %for.end31.i, label %for.body21.i
+
+for.body21.i:                                     ; preds = %entry
+  %arrayidx23.i = getelementptr inbounds [256 x i32], [256 x i32]* %count.i, i32 0, i32 1
+  %tmp20 = load i32, i32* %arrayidx23.i, align 4, !tbaa !0
+  store i32 %tmp20, i32* %ptr, align 4, !tbaa !0
+  br label %for.end31.i
+
+for.end31.i:                                      ; preds = %for.body21.i, %entry
+  %tmp21 = load i8*, i8** @debw, align 4, !tbaa !4
+  tail call void @free(i8* %tmp21)
+  ret void
+}
+
+declare void @free(i8* nocapture)
+
+attributes #0 = { ssp "stack-protector-buffer-size"="8" }
+
+!0 = !{!1, !1, i64 0}
+!1 = !{!"int", !2, i64 0}
+!2 = !{!"omnipotent char", !3, i64 0}
+!3 = !{!"Simple C/C++ TBAA"}
+!4 = !{!5, !5, i64 0}
+!5 = !{!"any pointer", !2, i64 0}