Index: lib/Target/ARM/ARMISelDAGToDAG.cpp
===================================================================
--- lib/Target/ARM/ARMISelDAGToDAG.cpp
+++ lib/Target/ARM/ARMISelDAGToDAG.cpp
@@ -2991,6 +2991,16 @@
     // Other cases are autogenerated.
     break;
   }
+  case ARMISD::WLS: {
+    SDValue Ops[] = { N->getOperand(1),   // Loop count
+                      N->getOperand(2),   // Exit target
+                      N->getOperand(0) };
+    SDNode *LoopStart =
+      CurDAG->getMachineNode(ARM::t2WhileLoopStart, dl, MVT::Other, Ops);
+    ReplaceUses(N, LoopStart);
+    CurDAG->RemoveDeadNode(N);
+    return;
+  }
   case ARMISD::BRCOND: {
     // Pattern: (ARMbrcond:void (bb:Other):$dst, (imm:i32):$cc)
     // Emits: (Bcc:void (bb:Other):$dst, (imm:i32):$cc)
Index: lib/Target/ARM/ARMISelLowering.h
===================================================================
--- lib/Target/ARM/ARMISelLowering.h
+++ lib/Target/ARM/ARMISelLowering.h
@@ -121,6 +121,8 @@
       WIN__CHKSTK,  // Windows' __chkstk call to do stack probing.
       WIN__DBZCHK,  // Windows' divide by zero check
 
+      WLS,          // Low-overhead loops, While Loop Start
+
       VCEQ,         // Vector compare equal.
       VCEQZ,        // Vector compare equal to zero.
       VCGE,         // Vector compare greater than or equal.
Index: lib/Target/ARM/ARMISelLowering.cpp
===================================================================
--- lib/Target/ARM/ARMISelLowering.cpp
+++ lib/Target/ARM/ARMISelLowering.cpp
@@ -571,6 +571,10 @@
   if (Subtarget->hasMVEIntegerOps())
     addMVEVectorTypes();
 
+  // Combine low-overhead loop intrinsics so that we can lower i1 types.
+  if (Subtarget->hasLOB())
+    setTargetDAGCombine(ISD::BRCOND);
+
   if (Subtarget->hasNEON()) {
     addDRTypeForNEON(MVT::v2f32);
     addDRTypeForNEON(MVT::v8i8);
@@ -1471,6 +1475,7 @@
   case ARMISD::VST2LN_UPD:    return "ARMISD::VST2LN_UPD";
   case ARMISD::VST3LN_UPD:    return "ARMISD::VST3LN_UPD";
   case ARMISD::VST4LN_UPD:    return "ARMISD::VST4LN_UPD";
+  case ARMISD::WLS:           return "ARMISD::WLS";
   }
   return nullptr;
 }
@@ -12725,6 +12730,33 @@
   return V;
 }
 
+static SDValue PerformHWLoopCombine(SDNode *N,
+                                    TargetLowering::DAGCombinerInfo &DCI,
+                                    const ARMSubtarget *ST) {
+  // Look for (brcond (xor test.set.loop.iterations, -1)
+  SDValue CC = N->getOperand(1);
+  if (CC->getOperand(0)->getOpcode() != ISD::INTRINSIC_W_CHAIN)
+    return SDValue();
+
+  SDValue Int = CC->getOperand(0);
+  unsigned IntOp = cast<ConstantSDNode>(Int.getOperand(1))->getZExtValue();
+  if (IntOp != Intrinsic::test_set_loop_iterations)
+    return SDValue();
+
+  SDLoc dl(Int);
+  SDValue Chain = N->getOperand(0);
+  SDValue Elements = Int.getOperand(2);
+  SDValue ExitBlock = N->getOperand(2);
+
+  // TODO: Once we start supporting tail predication, we can add another
+  // operand to WLS for the number of elements processed in a vector loop.
+
+  SDValue Ops[] = { Chain, Elements, ExitBlock };
+  SDValue Res = DCI.DAG.getNode(ARMISD::WLS, dl, MVT::Other, Ops);
+  DCI.DAG.ReplaceAllUsesOfValueWith(Int.getValue(1), Int.getOperand(0));
+  return Res;
+}
+
 /// PerformBRCONDCombine - Target-specific DAG combining for ARMISD::BRCOND.
 SDValue
 ARMTargetLowering::PerformBRCONDCombine(SDNode *N, SelectionDAG &DAG) const {
@@ -12956,6 +12988,7 @@
   case ISD::OR:         return PerformORCombine(N, DCI, Subtarget);
   case ISD::XOR:        return PerformXORCombine(N, DCI, Subtarget);
   case ISD::AND:        return PerformANDCombine(N, DCI, Subtarget);
+  case ISD::BRCOND:     return PerformHWLoopCombine(N, DCI, Subtarget);
   case ARMISD::ADDC:
   case ARMISD::SUBC:    return PerformAddcSubcCombine(N, DCI, Subtarget);
   case ARMISD::SUBE:    return PerformAddeSubeCombine(N, DCI, Subtarget);
Index: lib/Target/ARM/ARMInstrInfo.td
===================================================================
--- lib/Target/ARM/ARMInstrInfo.td
+++ lib/Target/ARM/ARMInstrInfo.td
@@ -99,6 +99,11 @@
                                         SDTCisSameAs<0, 4>,
                                         SDTCisSameAs<0, 5>]>;
 
+// TODO Add another operand for 'Size' so that we can re-use this node when we
+// start supporting *TP versions.
+def SDT_ARMWhileLoop : SDTypeProfile<0, 2, [SDTCisVT<0, i32>,
+                                            SDTCisVT<1, OtherVT>]>;
+
 def ARMSmlald        : SDNode<"ARMISD::SMLALD", SDT_LongMac>;
 def ARMSmlaldx       : SDNode<"ARMISD::SMLALDX", SDT_LongMac>;
 def ARMSmlsld        : SDNode<"ARMISD::SMLSLD", SDT_LongMac>;
@@ -213,6 +218,9 @@
 def ARMsmlaltb      : SDNode<"ARMISD::SMLALTB", SDT_LongMac, []>;
 def ARMsmlaltt      : SDNode<"ARMISD::SMLALTT", SDT_LongMac, []>;
 
+def ARMWLS : SDNode<"ARMISD::WLS", SDT_ARMWhileLoop,
+                    [SDNPHasChain]>;
+
 //===----------------------------------------------------------------------===//
 // ARM Flag Definitions.
 
Index: lib/Target/ARM/ARMInstrThumb2.td
===================================================================
--- lib/Target/ARM/ARMInstrThumb2.td
+++ lib/Target/ARM/ARMInstrThumb2.td
@@ -5215,11 +5215,19 @@
   t2PseudoInst<(outs GPRlr:$Rm), (ins GPRlr:$Rn, imm0_7:$size),
                4, IIC_Br, []>, Sched<[WriteBr]>;
 
-let isBranch = 1, isTerminator = 1, hasSideEffects = 1 in
+let isBranch = 1, isTerminator = 1, hasSideEffects = 1 in {
+def t2WhileLoopStart :
+    t2PseudoInst<(outs),
+                 (ins rGPR:$elts, brtarget:$target),
+                 4, IIC_Br, []>,
+                 Sched<[WriteBr]>;
+
 def t2LoopEnd :
   t2PseudoInst<(outs), (ins GPRlr:$elts, brtarget:$target),
   8, IIC_Br, []>, Sched<[WriteBr]>;
 
+} // end isBranch, isTerminator, hasSideEffects
+
 } // end isNotDuplicable
 
 class CS<string iname, bits<4> opcode, list<dag> pattern=[]>
Index: lib/Target/ARM/ARMLowOverheadLoops.cpp
===================================================================
--- lib/Target/ARM/ARMLowOverheadLoops.cpp
+++ lib/Target/ARM/ARMLowOverheadLoops.cpp
@@ -105,15 +105,20 @@
   LLVM_DEBUG(dbgs() << "ARM Loops: Processing " << *ML);
 
   auto IsLoopStart = [](MachineInstr &MI) {
-    return MI.getOpcode() == ARM::t2DoLoopStart;
+    return MI.getOpcode() == ARM::t2DoLoopStart ||
+           MI.getOpcode() == ARM::t2WhileLoopStart;
   };
 
-  auto SearchForStart =
-    [&IsLoopStart](MachineBasicBlock *MBB) -> MachineInstr* {
+  // Search the given block for a loop start instruction. If one isn't found,
+  // and there's only one predecessor block, search that one too.
+  std::function<MachineInstr*(MachineBasicBlock*)> SearchForStart =
+    [&IsLoopStart, &SearchForStart](MachineBasicBlock *MBB) -> MachineInstr* {
     for (auto &MI : *MBB) {
       if (IsLoopStart(MI))
         return &MI;
     }
+    if (MBB->pred_size() == 1)
+      return SearchForStart(*MBB->pred_begin());
     return nullptr;
   };
 
@@ -122,8 +127,24 @@
   MachineInstr *End = nullptr;
   bool Revert = false;
 
-  if (auto *Preheader = ML->getLoopPreheader())
+  if (auto *Preheader = ML->getLoopPreheader()) {
     Start = SearchForStart(Preheader);
+  } else {
+    LLVM_DEBUG(dbgs() << "ARM Loops: Failed to find loop preheader!\n"
+               << " - Performing manual predecessor search.\n");
+    MachineBasicBlock *Pred = nullptr;
+    for (auto *MBB : ML->getHeader()->predecessors()) {
+      if (!ML->contains(MBB)) {
+        if (Pred) {
+          LLVM_DEBUG(dbgs() << " - Found multiple out-of-loop preds.\n");
+          Start = nullptr;
+          break;
+        }
+        Pred = MBB;
+        Start = SearchForStart(MBB);
+      }
+    }
+  }
 
   // Find the low-overhead loop components and decide whether or not to fall
   // back to a normal loop.
@@ -212,15 +233,21 @@
       break;
     }
 
+    unsigned Opc = Start->getOpcode() == ARM::t2DoLoopStart ?
+      ARM::t2DLS : ARM::t2WLS;
     MachineInstrBuilder MIB =
-      BuildMI(*MBB, InsertPt, InsertPt->getDebugLoc(), TII->get(ARM::t2DLS));
-    if (InsertPt != Start)
-      InsertPt->eraseFromParent();
+      BuildMI(*MBB, InsertPt, InsertPt->getDebugLoc(), TII->get(Opc));
 
     MIB.addDef(ARM::LR);
     MIB.add(Start->getOperand(0));
-    LLVM_DEBUG(dbgs() << "ARM Loops: Inserted DLS: " << *MIB);
+    if (Opc == ARM::t2WLS)
+      MIB.add(Start->getOperand(1));
+
+    if (InsertPt != Start)
+      InsertPt->eraseFromParent();
     Start->eraseFromParent();
+    LLVM_DEBUG(dbgs() << "ARM Loops: Inserted start: " << *MIB);
+    return &*MIB;
   };
 
   // Combine the LoopDec and LoopEnd instructions into LE(TP).
@@ -234,20 +261,9 @@
     MIB.add(End->getOperand(1));
     LLVM_DEBUG(dbgs() << "ARM Loops: Inserted LE: " << *MIB);
 
-    // If there is a branch after loop end, which branches to the fallthrough
-    // block, remove the branch.
-    MachineBasicBlock *Latch = End->getParent();
-    MachineInstr *Terminator = &Latch->instr_back();
-    if (End != Terminator) {
-      MachineBasicBlock *Exit = ML->getExitBlock();
-      if (Latch->isLayoutSuccessor(Exit)) {
-        LLVM_DEBUG(dbgs() << "ARM Loops: Removing loop exit branch: "
-                   << *Terminator);
-        Terminator->eraseFromParent();
-      }
-    }
     End->eraseFromParent();
     Dec->eraseFromParent();
+    return &*MIB;
   };
 
   // Generate a subs, or sub and cmp, and a branch instead of an LE.
@@ -282,12 +298,28 @@
     Dec->eraseFromParent();
   };
 
+  // If there is an unconditional branch, after I, that just branches to the
+  // next block, remove it.
+  auto RemoveDeadBranch = [](MachineInstr *I) {
+    MachineBasicBlock *BB = I->getParent();
+    MachineInstr *Terminator = &BB->instr_back();
+    if (Terminator->isUnconditionalBranch() && I != Terminator) {
+      MachineBasicBlock *Succ = Terminator->getOperand(0).getMBB();
+      if (BB->isLayoutSuccessor(Succ)) {
+        LLVM_DEBUG(dbgs() << "ARM Loops: Removing branch: " << *Terminator);
+        Terminator->eraseFromParent();
+      }
+    }
+  };
+
   if (Revert) {
     Start->eraseFromParent();
     ExpandBranch(Dec, End);
   } else {
-    ExpandLoopStart(ML, Start);
-    ExpandLoopEnd(ML, Dec, End);
+    Start = ExpandLoopStart(ML, Start);
+    RemoveDeadBranch(Start);
+    End = ExpandLoopEnd(ML, Dec, End);
+    RemoveDeadBranch(End);
   }
 }
 
Index: lib/Target/ARM/ARMTargetTransformInfo.cpp
===================================================================
--- lib/Target/ARM/ARMTargetTransformInfo.cpp
+++ lib/Target/ARM/ARMTargetTransformInfo.cpp
@@ -806,6 +806,7 @@
       default:
         break;
       case Intrinsic::set_loop_iterations:
+      case Intrinsic::test_set_loop_iterations:
       case Intrinsic::loop_decrement:
       case Intrinsic::loop_decrement_reg:
         return true;
@@ -841,6 +842,7 @@
   LLVMContext &C = L->getHeader()->getContext();
   HWLoopInfo.CounterInReg = true;
   HWLoopInfo.IsNestingLegal = false;
+  HWLoopInfo.PerformEntryTest = true;
   HWLoopInfo.CountType = Type::getInt32Ty(C);
   HWLoopInfo.LoopDecrement = ConstantInt::get(HWLoopInfo.CountType, 1);
   return true;
Index: test/Transforms/HardwareLoops/ARM/do-rem.ll
===================================================================
--- test/Transforms/HardwareLoops/ARM/do-rem.ll
+++ test/Transforms/HardwareLoops/ARM/do-rem.ll
@@ -3,10 +3,14 @@
 @g = common local_unnamed_addr global i32* null, align 4
 
 ; CHECK-LABEL: do_with_i32_urem
+; CHECK: entry:
+; CHECK: [[TEST:%[^ ]+]] = call i1 @llvm.test.set.loop.iterations.i32(i32 %n)
+; CHECK: br i1 [[TEST]], label %while.body.preheader, label %while.end
+
 ; CHECK: while.body.preheader:
-; CHECK: call void @llvm.set.loop.iterations.i32(i32 %n)
 ; CHECK-NEXT: br label %while.body
 
+; CHECK: while.body:
 ; CHECK: [[REM:%[^ ]+]] = phi i32 [ %n, %while.body.preheader ], [ [[LOOP_DEC:%[^ ]+]], %while.body ]
 ; CHECK: [[LOOP_DEC]] = call i32 @llvm.loop.decrement.reg.i32.i32.i32(i32 [[REM]], i32 1)
 ; CHECK: [[CMP:%[^ ]+]] = icmp ne i32 [[LOOP_DEC]], 0
@@ -38,10 +42,14 @@
 }
 
 ; CHECK-LABEL: do_with_i32_srem
+; CHECK: entry:
+; CHECK: [[TEST:%[^ ]+]] = call i1 @llvm.test.set.loop.iterations.i32(i32 %n)
+; CHECK: br i1 [[TEST]], label %while.body.preheader, label %while.end
+
 ; CHECK: while.body.preheader:
-; CHECK: call void @llvm.set.loop.iterations.i32(i32 %n)
 ; CHECK-NEXT: br label %while.body
 
+; CHECK: while.body:
 ; CHECK: [[REM:%[^ ]+]] = phi i32 [ %n, %while.body.preheader ], [ [[LOOP_DEC:%[^ ]+]], %while.body ]
 ; CHECK: [[LOOP_DEC]] = call i32 @llvm.loop.decrement.reg.i32.i32.i32(i32 [[REM]], i32 1)
 ; CHECK: [[CMP:%[^ ]+]] = icmp ne i32 [[LOOP_DEC]], 0
@@ -73,10 +81,14 @@
 }
 
 ; CHECK-LABEL: do_with_i32_udiv
+; CHECK: entry:
+; CHECK: [[TEST:%[^ ]+]] = call i1 @llvm.test.set.loop.iterations.i32(i32 %n)
+; CHECK: br i1 [[TEST]], label %while.body.preheader, label %while.end
+
 ; CHECK: while.body.preheader:
-; CHECK: call void @llvm.set.loop.iterations.i32(i32 %n)
 ; CHECK-NEXT: br label %while.body
 
+; CHECK: while.body:
 ; CHECK: [[REM:%[^ ]+]] = phi i32 [ %n, %while.body.preheader ], [ [[LOOP_DEC:%[^ ]+]], %while.body ]
 ; CHECK: [[LOOP_DEC]] = call i32 @llvm.loop.decrement.reg.i32.i32.i32(i32 [[REM]], i32 1)
 ; CHECK: [[CMP:%[^ ]+]] = icmp ne i32 [[LOOP_DEC]], 0
@@ -108,10 +120,14 @@
 }
 
 ; CHECK-LABEL: do_with_i32_sdiv
+; CHECK: entry:
+; CHECK: [[TEST:%[^ ]+]] = call i1 @llvm.test.set.loop.iterations.i32(i32 %n)
+; CHECK: br i1 [[TEST]], label %while.body.preheader, label %while.end
+
 ; CHECK: while.body.preheader:
-; CHECK: call void @llvm.set.loop.iterations.i32(i32 %n)
 ; CHECK-NEXT: br label %while.body
 
+; CHECK: while.body:
 ; CHECK: [[REM:%[^ ]+]] = phi i32 [ %n, %while.body.preheader ], [ [[LOOP_DEC:%[^ ]+]], %while.body ]
 ; CHECK: [[LOOP_DEC]] = call i32 @llvm.loop.decrement.reg.i32.i32.i32(i32 [[REM]], i32 1)
 ; CHECK: [[CMP:%[^ ]+]] = icmp ne i32 [[LOOP_DEC]], 0
@@ -143,7 +159,7 @@
 }
 
 ; CHECK-LABEL: do_with_i64_urem
-; CHECK-NOT: llvm.set.loop.iterations
+; CHECK-NOT: llvm.{{.*}}.loop.iterations
 ; CHECK-NOT: llvm.loop.decrement
 define i64 @do_with_i64_urem(i32 %n) {
 entry:
@@ -172,7 +188,7 @@
 }
 
 ; CHECK-LABEL: do_with_i64_srem
-; CHECK-NOT: llvm.set.loop.iterations
+; CHECK-NOT: llvm.{{.*}}.loop.iterations
 ; CHECK-NOT: llvm.loop.decrement
 define i64 @do_with_i64_srem(i32 %n) {
 entry:
@@ -201,7 +217,7 @@
 }
 
 ; CHECK-LABEL: do_with_i64_udiv
-; CHECK-NOT: llvm.set.loop.iterations
+; CHECK-NOT: llvm.{{.*}}.loop.iterations
 ; CHECK-NOT: llvm.loop.decrement
 define i64 @do_with_i64_udiv(i32 %n) {
 entry:
@@ -230,7 +246,7 @@
 }
 
 ; CHECK-LABEL: do_with_i64_sdiv
-; CHECK-NOT: call void @llvm.set.loop.iterations
+; CHECK-NOT: call void @llvm.{{.*}}.loop.iterations
 ; CHECK-NOT: call i32 @llvm.loop.decrement
 define i64 @do_with_i64_sdiv(i32 %n) {
 entry:
Index: test/Transforms/HardwareLoops/ARM/fp-emulation.ll
===================================================================
--- test/Transforms/HardwareLoops/ARM/fp-emulation.ll
+++ test/Transforms/HardwareLoops/ARM/fp-emulation.ll
@@ -2,12 +2,16 @@
 ; RUN: opt -mtriple=thumbv8.1m.main-arm-none-eabi -mattr=+soft-float -hardware-loops -disable-arm-loloops=false %s -S -o - | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-SOFT
 
 ; CHECK-LABEL: test_fptosi
-; CHECK: while.body.lr.ph:
+; CHECK-FP: entry:
 ; CHECK-FP: [[CMP:%[^ ]+]] = icmp ugt i32 %n, 1
 ; CHECK-FP: [[COUNT:%[^ ]+]] = select i1 [[CMP]], i32 %n, i32 1
-; CHECK-FP: call void @llvm.set.loop.iterations.i32(i32 [[COUNT]])
-; CHECK-FP-NEXT: br label %while.body
+; CHECK-FP: [[TEST:%[^ ]+]] = call i1 @llvm.test.set.loop.iterations.i32(i32 [[COUNT]])
+; CHECK-FP: br i1 [[TEST]], label %while.body.lr.ph, label %cleanup
+
+; CHECK: while.body.lr.ph:
+; CHECK-FP: br label %while.body
 
+; CHECK: while.body:
 ; CHECK-FP: [[REM:%[^ ]+]] = phi i32 [ [[COUNT]], %while.body.lr.ph ], [ [[LOOP_DEC:%[^ ]+]], %if.end4 ]
 ; CHECK-FP: [[LOOP_DEC]] = call i32 @llvm.loop.decrement.reg.i32.i32.i32(i32 [[REM]], i32 1)
 ; CHECK-FP: [[CMP:%[^ ]+]] = icmp ne i32 [[LOOP_DEC]], 0
@@ -53,12 +57,16 @@
 }
 
 ; CHECK-LABEL: test_fptoui
-; CHECK-FP: while.body.lr.ph:
+; CHECK-FP: entry:
 ; CHECK-FP: [[CMP:%[^ ]+]] = icmp ugt i32 %n, 1
 ; CHECK-FP: [[COUNT:%[^ ]+]] = select i1 [[CMP]], i32 %n, i32 1
-; CHECK-FP: call void @llvm.set.loop.iterations.i32(i32 [[COUNT]])
-; CHECK-FP-NEXT: br label %while.body
+; CHECK-FP: [[TEST:%[^ ]+]] = call i1 @llvm.test.set.loop.iterations.i32(i32 [[COUNT]])
+; CHECK-FP: br i1 [[TEST]], label %while.body.lr.ph, label %cleanup
+
+; CHECK: while.body.lr.ph:
+; CHECK-FP: br label %while.body
 
+; CHECK: while.body:
 ; CHECK-FP: [[REM:%[^ ]+]] = phi i32 [ [[COUNT]], %while.body.lr.ph ], [ [[LOOP_DEC:%[^ ]+]], %if.end4 ]
 ; CHECK-FP: [[LOOP_DEC]] = call i32 @llvm.loop.decrement.reg.i32.i32.i32(i32 [[REM]], i32 1)
 ; CHECK-FP: [[CMP:%[^ ]+]] = icmp ne i32 [[LOOP_DEC]], 0
@@ -104,12 +112,16 @@
 }
 
 ; CHECK-LABEL: load_store_float
-; CHECK: while.body.lr.ph:
+; CHECK: entry:
 ; CHECK: [[CMP:%[^ ]+]] = icmp ugt i32 %n, 1
 ; CHECK: [[COUNT:%[^ ]+]] = select i1 [[CMP]], i32 %n, i32 1
-; CHECK: call void @llvm.set.loop.iterations.i32(i32 [[COUNT]])
-; CHECK-NEXT: br label %while.body
+; CHECK: [[TEST:%[^ ]+]] = call i1 @llvm.test.set.loop.iterations.i32(i32 [[COUNT]])
+; CHECK: br i1 [[TEST]], label %while.body.lr.ph, label %cleanup
 
+; CHECK: while.body.lr.ph:
+; CHECK: br label %while.body
+
+; CHECK: while.body:
 ; CHECK: [[REM:%[^ ]+]] = phi i32 [ [[COUNT]], %while.body.lr.ph ], [ [[LOOP_DEC:%[^ ]+]], %if.end4 ]
 ; CHECK: [[LOOP_DEC]] = call i32 @llvm.loop.decrement.reg.i32.i32.i32(i32 [[REM]], i32 1)
 ; CHECK: [[CMP:%[^ ]+]] = icmp ne i32 [[LOOP_DEC]], 0
@@ -152,17 +164,19 @@
 }
 
 ; CHECK-LABEL: fp_add
-; CHECK: while.body.lr.ph:
-
 ; CHECK-SOFT-NOT: call void @llvm.set.loop.iterations
+; CHECK-SOFT-NOT: call i32 @llvm.loop.decrement
 
+; CHECK-FP: entry:
 ; CHECK-FP: [[CMP:%[^ ]+]] = icmp ugt i32 %n, 1
 ; CHECK-FP: [[COUNT:%[^ ]+]] = select i1 [[CMP]], i32 %n, i32 1
-; CHECK-FP: call void @llvm.set.loop.iterations.i32(i32 [[COUNT]])
-; CHECK: br label %while.body
+; CHECK-FP: [[TEST:%[^ ]+]] = call i1 @llvm.test.set.loop.iterations.i32(i32 [[COUNT]])
+; CHECK-FP: br i1 [[TEST]], label %while.body.lr.ph, label %cleanup
 
-; CHECK-SOFT-NOT: call i32 @llvm.loop.decrement
+; CHECK: while.body.lr.ph:
+; CHECK-FP: br label %while.body
 
+; CHECK: while.body:
 ; CHECK-FP: [[REM:%[^ ]+]] = phi i32 [ [[COUNT]], %while.body.lr.ph ], [ [[LOOP_DEC:%[^ ]+]], %if.end4 ]
 ; CHECK-FP: [[LOOP_DEC]] = call i32 @llvm.loop.decrement.reg.i32.i32.i32(i32 [[REM]], i32 1)
 ; CHECK-FP: [[CMP:%[^ ]+]] = icmp ne i32 [[LOOP_DEC]], 0
Index: test/Transforms/HardwareLoops/ARM/simple-do.ll
===================================================================
--- test/Transforms/HardwareLoops/ARM/simple-do.ll
+++ test/Transforms/HardwareLoops/ARM/simple-do.ll
@@ -3,7 +3,7 @@
 ; RUN: opt -mtriple=thumbv8.1m.main-arm-none-eabi -mattr=-lob -hardware-loops %s -S -o - | FileCheck %s --check-prefix=DISABLED
 ; RUN: llc -mtriple=thumbv8.1m.main-arm-none-eabi -disable-arm-loloops=false %s -o - | FileCheck %s --check-prefix=CHECK-LLC
 
-; DISABLED-NOT: llvm.set.loop.iterations
+; DISABLED-NOT: llvm.{{.*}}.loop.iterations
 ; DISABLED-NOT: llvm.loop.decrement
 
 @g = common local_unnamed_addr global i32* null, align 4
@@ -46,9 +46,12 @@
 }
 
 ; CHECK-LABEL: do_inc1
+; CHECK: entry:
+; CHECK: [[TEST:%[^ ]+]] = call i1 @llvm.test.set.loop.iterations.i32(i32 %n)
+; CHECK: br i1 [[TEST]], label %while.body.lr.ph, label %while.end
+
 ; CHECK: while.body.lr.ph:
-; CHECK: call void @llvm.set.loop.iterations.i32(i32 %n)
-; CHECK-NEXT: br label %while.body
+; CHECK: br label %while.body
 
 ; CHECK: [[REM:%[^ ]+]] = phi i32 [ %n, %while.body.lr.ph ], [ [[LOOP_DEC:%[^ ]+]], %while.body ]
 ; CHECK: [[LOOP_DEC]] = call i32 @llvm.loop.decrement.reg.i32.i32.i32(i32 [[REM]], i32 1)
@@ -56,12 +59,12 @@
 ; CHECK: br i1 [[CMP]], label %while.body, label %while.end.loopexit
 
 ; CHECK-LLC-LABEL:do_inc1:
-; CHECK-LLC:        dls lr,
+; CHECK-LLC:        wls lr, {{.*}}, [[LOOP_EXIT:.[LBB_0-3]+]]
 ; CHECK-LLC-NOT:    mov lr,
 ; CHECK-LLC:      [[LOOP_HEADER:\.LBB[0-9_]+]]:
 ; CHECK-LLC:        le lr, [[LOOP_HEADER]]
 ; CHECK-LLC-NOT:    b [[LOOP_EXIT:\.LBB[0-9_]+]]
-; CHECK-LLC:      [[LOOP_EXIT:\.LBB[0-9_]+]]:
+; CHECK-LLC:      [[LOOP_EXIT]]:
 
 define i32 @do_inc1(i32 %n) {
 entry:
@@ -91,12 +94,15 @@
 }
 
 ; CHECK-LABEL: do_inc2
-; CHECK: while.body.lr.ph:
+; CHECK: entry:
 ; CHECK: [[ROUND:%[^ ]+]] = add i32 %n, -1
 ; CHECK: [[HALVE:%[^ ]+]] = lshr i32 [[ROUND]], 1
 ; CHECK: [[COUNT:%[^ ]+]] = add nuw i32 [[HALVE]], 1
-; CHECK: call void @llvm.set.loop.iterations.i32(i32 [[COUNT]])
-; CHECK-NEXT: br label %while.body
+; CHECK: [[TEST:%[^ ]+]] = call i1 @llvm.test.set.loop.iterations.i32(i32 [[COUNT]])
+; CHECK: br i1 [[TEST]], label %while.body.lr.ph, label %while.end
+
+; CHECK: while.body.lr.ph:
+; CHECK: br label %while.body
 
 ; CHECK: [[REM:%[^ ]+]] = phi i32 [ [[COUNT]], %while.body.lr.ph ], [ [[LOOP_DEC:%[^ ]+]], %while.body ]
 ; CHECK: [[LOOP_DEC]] = call i32 @llvm.loop.decrement.reg.i32.i32.i32(i32 [[REM]], i32 1)
@@ -105,12 +111,12 @@
 
 ; CHECK-LLC:      do_inc2:
 ; CHECK-LLC-NOT:    mov lr,
-; CHECK-LLC:        dls lr,
+; CHECK-LLC:        wls lr, {{.*}}, [[LOOP_EXIT:.LBB[0-9_]+]]
 ; CHECK-LLC-NOT:    mov lr,
 ; CHECK-LLC:      [[LOOP_HEADER:\.LBB[0-9._]+]]:
 ; CHECK-LLC:        le lr, [[LOOP_HEADER]]
 ; CHECK-LLC-NOT:    b [[LOOP_EXIT:\.LBB[0-9._]+]]
-; CHECK-LLC:      [[LOOP_EXIT:\.LBB[0-9_]+]]:
+; CHECK-LLC:      [[LOOP_EXIT]]:
 
 define i32 @do_inc2(i32 %n) {
 entry:
@@ -141,15 +147,18 @@
 
 ; CHECK-LABEL: do_dec2
 
-; CHECK: while.body.lr.ph:
+; CHECK: entry:
 ; CHECK: [[ROUND:%[^ ]+]] = add i32 %n, 1
 ; CHECK: [[CMP:%[^ ]+]] = icmp slt i32 %n, 2
 ; CHECK: [[SMIN:%[^ ]+]] = select i1 [[CMP]], i32 %n, i32 2
 ; CHECK: [[SUB:%[^ ]+]] = sub i32 [[ROUND]], [[SMIN]]
 ; CHECK: [[HALVE:%[^ ]+]] = lshr i32 [[SUB]], 1
 ; CHECK: [[COUNT:%[^ ]+]] = add nuw i32 [[HALVE]], 1
-; CHECK: call void @llvm.set.loop.iterations.i32(i32 [[COUNT]])
-; CHECK-NEXT: br label %while.body
+; CHECK: [[TEST:%[^ ]+]] = call i1 @llvm.test.set.loop.iterations.i32(i32 [[COUNT]])
+; CHECK: br i1 [[TEST]], label %while.body.lr.ph, label %while.end
+
+; CHECK: while.body.lr.ph:
+; CHECK: br label %while.body
 
 ; CHECK: [[REM:%[^ ]+]] = phi i32 [ [[COUNT]], %while.body.lr.ph ], [ [[LOOP_DEC:%[^ ]+]], %while.body ]
 ; CHECK: [[LOOP_DEC]] = call i32 @llvm.loop.decrement.reg.i32.i32.i32(i32 [[REM]], i32 1)
@@ -158,12 +167,12 @@
 
 ; CHECK-LLC:      do_dec2
 ; CHECK-LLC-NOT:    mov lr,
-; CHECK-LLC:        dls lr,
+; CHECK-LLC:        wls lr, {{.*}}, [[LOOP_EXIT:.LBB[0-9_]+]]
 ; CHECK-LLC-NOT:    mov lr,
 ; CHECK-LLC:      [[LOOP_HEADER:\.LBB[0-9_]+]]:
 ; CHECK-LLC:        le lr, [[LOOP_HEADER]]
 ; CHECK-LLC-NOT:    b .
-; CHECK-LLC:      @ %while.end
+; CHECK-LLC:      [[LOOP_EXIT]]:
 define i32 @do_dec2(i32 %n) {
 entry:
   %cmp6 = icmp sgt i32 %n, 0
Index: test/Transforms/HardwareLoops/ARM/structure.ll
===================================================================
--- test/Transforms/HardwareLoops/ARM/structure.ll
+++ test/Transforms/HardwareLoops/ARM/structure.ll
@@ -109,6 +109,35 @@
   ret i32 0
 }
 
+; CHECK-LABEL: pre_existing_test_set
+; CHECK: call i1 @llvm.test.set.loop.iterations
+; CHECK-NOT: llvm.set{{.*}}.loop.iterations
+; CHECK: call i32 @llvm.loop.decrement.reg.i32.i32.i32(i32 %0, i32 1)
+; CHECK-NOT: call i32 @llvm.loop.decrement.reg
+define i32 @pre_existing_test_set(i32 %n, i32* nocapture %p, i32* nocapture readonly %q) {
+entry:
+  %guard = call i1 @llvm.test.set.loop.iterations.i32(i32 %n)
+  br i1 %guard, label %while.preheader, label %while.end
+
+while.preheader:
+  br label %while.body
+
+while.body:                                       ; preds = %while.body, %entry
+  %q.addr.05 = phi i32* [ %incdec.ptr, %while.body ], [ %q, %while.preheader ]
+  %p.addr.04 = phi i32* [ %incdec.ptr1, %while.body ], [ %p, %while.preheader ]
+  %0 = phi i32 [ %n, %while.preheader ], [ %2, %while.body ]
+  %incdec.ptr = getelementptr inbounds i32, i32* %q.addr.05, i32 1
+  %1 = load i32, i32* %q.addr.05, align 4
+  %incdec.ptr1 = getelementptr inbounds i32, i32* %p.addr.04, i32 1
+  store i32 %1, i32* %p.addr.04, align 4
+  %2 = call i32 @llvm.loop.decrement.reg.i32.i32.i32(i32 %0, i32 1)
+  %3 = icmp ne i32 %2, 0
+  br i1 %3, label %while.body, label %while.end
+
+while.end:                                        ; preds = %while.body
+  ret i32 0
+}
+
 ; CHECK-LABEL: pre_existing_inner
 ; CHECK-NOT: llvm.set.loop.iterations
 ; CHECK: while.cond1.preheader.us:
@@ -223,14 +252,16 @@
 }
 
 ; CHECK-LABEL: search
+; CHECK: entry:
+; CHECK:   [[TEST:%[^ ]+]] = call i1 @llvm.test.set.loop.iterations.i32(i32 %N)
+; CHECK:   br i1 [[TEST]], label %for.body.preheader, label %for.cond.cleanup
 ; CHECK: for.body.preheader:
-; CHECK: call void @llvm.set.loop.iterations.i32(i32 %N)
-; CHECK: br label %for.body
+; CHECK:   br label %for.body
 ; CHECK: for.body:
 ; CHECK: for.inc:
-; CHECK: [[LOOP_DEC:%[^ ]+]] = call i32 @llvm.loop.decrement.reg.i32.i32.i32
-; CHECK: [[CMP:%[^ ]+]] = icmp ne i32 [[LOOP_DEC]], 0
-; CHECK: br i1 [[CMP]], label %for.body, label %for.cond.cleanup
+; CHECK:   [[LOOP_DEC:%[^ ]+]] = call i32 @llvm.loop.decrement.reg.i32.i32.i32
+; CHECK:   [[CMP:%[^ ]+]] = icmp ne i32 [[LOOP_DEC]], 0
+; CHECK:   br i1 [[CMP]], label %for.body, label %for.cond.cleanup
 define i32 @search(i8* nocapture readonly %c, i32 %N) {
 entry:
   %cmp11 = icmp eq i32 %N, 0
@@ -272,20 +303,20 @@
 }
 
 ; CHECK-LABEL: unroll_inc_int
-; CHECK: call void @llvm.set.loop.iterations.i32(i32 %N)
+; CHECK: call i1 @llvm.test.set.loop.iterations.i32(i32 %N)
 ; CHECK: call i32 @llvm.loop.decrement.reg.i32.i32.i32(
 
 ; TODO: We should be able to support the unrolled loop body.
-; CHECK-UNROLL-LABEL: unroll_inc_int:
+; CHECK-UNROLL-LABEL: unroll_inc_int
 ; CHECK-UNROLL:     [[PREHEADER:.LBB[0-9_]+]]: @ %for.body.preheader
 ; CHECK-UNROLL-NOT: dls
 ; CHECK-UNROLL:     [[LOOP:.LBB[0-9_]+]]: @ %for.body
 ; CHECK-UNROLL-NOT: le lr, [[LOOP]]
 ; CHECK-UNROLL:     bne [[LOOP]]
-; CHECK-UNROLL:     %for.body.epil.preheader
-; CHECK-UNROLL:     dls
-; CHECK-UNROLL:     %for.body.epil
-; CHECK-UNROLL:     le
+; CHECK-UNROLL:     wls lr, lr, [[EXIT:.LBB[0-9_]+]]
+; CHECK-UNROLL:     [[EPIL:.LBB[0-9_]+]]:
+; CHECK-UNROLL:     le lr, [[EPIL]]
+; CHECK-UNROLL-NEXT: [[EXIT]]
 
 define void @unroll_inc_int(i32* nocapture %a, i32* nocapture readonly %b, i32* nocapture readonly %c, i32 %N) {
 entry:
@@ -310,24 +341,27 @@
 }
 
 ; CHECK-LABEL: unroll_inc_unsigned
-; CHECK: call void @llvm.set.loop.iterations.i32(i32 %N)
+; CHECK: call i1 @llvm.test.set.loop.iterations.i32(i32 %N)
 ; CHECK: call i32 @llvm.loop.decrement.reg.i32.i32.i32(
 
 ; CHECK-LLC-LABEL: unroll_inc_unsigned:
-; CHECK-LLC: dls lr, [[COUNT:r[0-9]+]]
-; CHECK-LLC: le  lr
+; CHECK-LLC: wls lr, r3, [[EXIT:.LBB[0-9_]+]]
+; CHECK-LLC: [[HEADER:.LBB[0-9_]+]]:
+; CHECK-LLC: le lr, [[HEADER]]
+; CHECK-LLC-NEXT: [[EXIT]]:
 
 ; TODO: We should be able to support the unrolled loop body.
-; CHECK-UNROLL-LABEL: unroll_inc_unsigned:
+; CHECK-UNROLL-LABEL: unroll_inc_unsigned
 ; CHECK-UNROLL:     [[PREHEADER:.LBB[0-9_]+]]: @ %for.body.preheader
 ; CHECK-UNROLL-NOT: dls
 ; CHECK-UNROLL:     [[LOOP:.LBB[0-9_]+]]: @ %for.body
 ; CHECK-UNROLL-NOT: le lr, [[LOOP]]
 ; CHECK-UNROLL:     bne [[LOOP]]
-; CHECK-UNROLL:     %for.body.epil.preheader
-; CHECK-UNROLL:     dls
-; CHECK-UNROLL:     %for.body.epil
-; CHECK-UNROLL:     le
+; CHECK-UNROLL:     wls lr, lr, [[EPIL_EXIT:.LBB[0-9_]+]]
+; CHECK-UNROLL: [[EPIL:.LBB[0-9_]+]]:
+; CHECK-UNROLL:     le lr, [[EPIL]]
+; CHECK-UNROLL: [[EPIL_EXIT]]:
+; CHECK-UNROLL:     pop
 define void @unroll_inc_unsigned(i32* nocapture %a, i32* nocapture readonly %b, i32* nocapture readonly %c, i32 %N) {
 entry:
   %cmp8 = icmp eq i32 %N, 0
@@ -351,21 +385,26 @@
 }
 
 ; CHECK-LABEL: unroll_dec_int
-; CHECK: call void @llvm.set.loop.iterations.i32(i32 %N)
+; CHECK: call i1 @llvm.test.set.loop.iterations.i32(i32 %N)
 ; CHECK: call i32 @llvm.loop.decrement.reg.i32.i32.i32(
 
 ; TODO: An unnecessary register is being held to hold COUNT, lr should just
 ; be used instead.
 ; CHECK-LLC-LABEL: unroll_dec_int:
-; CHECK-LLC: dls lr, [[COUNT:r[0-9]+]]
-; CHECK-LLC: subs  [[COUNT]], #1
-; CHECK-LLC: le  lr
+; CHECK-LLC: wls lr, r3, [[EXIT:.LBB[0-9_]+]]
+; CHECK-LLC: [[HEADER:.LBB[0-9_]+]]:
+; CHECK-LLC: le lr, [[HEADER]]
+; CHECK-LLC-NEXT: [[EXIT]]:
 
 ; CHECK-UNROLL-LABEL: unroll_dec_int
-; CHECK-UNROLL: dls lr
-; CHECK-UNROLL: le lr
-; CHECK-UNROLL: dls lr
-; CHECK-UNROLL: le lr
+; CHECK-UNROLL:         wls lr, {{.*}}, [[PROLOGUE_EXIT:.LBB[0-9_]+]]
+; CHECK-UNROLL-NEXT: [[PROLOGUE:.LBB[0-9_]+]]:
+; CHECK-UNROLL:         le lr, [[PROLOGUE]]
+; CHECK-UNROLL-NEXT: [[PROLOGUE_EXIT:.LBB[0-9_]+]]:
+; CHECK-UNROLL:         wls lr, lr, [[EXIT:.LBB[0-9_]+]]
+; CHECK-UNROLL:      [[BODY:.LBB[0-9_]+]]:
+; CHECK-UNROLL:         le lr, [[BODY]]
+; CHECK-UNROLL-NEXT: [[EXIT]]:
 define void @unroll_dec_int(i32* nocapture %a, i32* nocapture readonly %b, i32* nocapture readonly %c, i32 %N) {
 entry:
   %cmp8 = icmp sgt i32 %N, 0
@@ -389,5 +428,6 @@
 }
 
 declare void @llvm.set.loop.iterations.i32(i32) #0
+declare i1 @llvm.test.set.loop.iterations.i32(i32) #0
 declare i32 @llvm.loop.decrement.reg.i32.i32.i32(i32, i32) #0
 
Index: test/Transforms/HardwareLoops/ARM/while.mir
===================================================================
--- /dev/null
+++ test/Transforms/HardwareLoops/ARM/while.mir
@@ -0,0 +1,125 @@
+# RUN: llc -mtriple=thumbv8.1m.main -mattr=+lob %s -run-pass=arm-low-overhead-loops --verify-machineinstrs -o - | FileCheck %s
+# CHECK: $lr = t2WLS
+# CHECK: $lr = t2LEUpdate renamable $lr
+
+--- |
+  target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
+  target triple = "thumbv8.1m.main-arm-unknown"
+  
+  ; Function Attrs: norecurse nounwind optsize
+  define dso_local arm_aapcscc void @copy(i16* nocapture %a, i16* nocapture readonly %b, i32 %N) {
+  entry:
+    %cmp4 = icmp eq i32 %N, 0
+    %0 = call i1 @llvm.test.set.loop.iterations.i32(i32 %N)
+    br i1 %0, label %while.body.preheader, label %while.end
+  
+  while.body.preheader:                             ; preds = %entry
+    br label %while.body
+  
+  while.body:                                       ; preds = %while.body, %while.body.preheader
+    %a.addr.06 = phi i16* [ %incdec.ptr1, %while.body ], [ %a, %while.body.preheader ]
+    %b.addr.05 = phi i16* [ %incdec.ptr, %while.body ], [ %b, %while.body.preheader ]
+    %1 = phi i32 [ %N, %while.body.preheader ], [ %3, %while.body ]
+    %incdec.ptr = getelementptr inbounds i16, i16* %b.addr.05, i32 1
+    %2 = load i16, i16* %b.addr.05, align 2, !tbaa !3
+    %incdec.ptr1 = getelementptr inbounds i16, i16* %a.addr.06, i32 1
+    store i16 %2, i16* %a.addr.06, align 2, !tbaa !3
+    %3 = call i32 @llvm.loop.decrement.reg.i32.i32.i32(i32 %1, i32 1)
+    %4 = icmp ne i32 %3, 0
+    br i1 %4, label %while.body, label %while.end
+  
+  while.end:                                        ; preds = %while.body, %entry
+    ret void
+  }
+  
+  declare i1 @llvm.test.set.loop.iterations.i32(i32) #1
+  declare i32 @llvm.loop.decrement.reg.i32.i32.i32(i32, i32) #1
+  
+  attributes #1 = { noduplicate nounwind }
+  attributes #2 = { nounwind }
+  
+  !llvm.module.flags = !{!0, !1}
+  
+  !0 = !{i32 1, !"wchar_size", i32 4}
+  !1 = !{i32 1, !"min_enum_size", i32 4}
+  !3 = !{!4, !4, i64 0}
+  !4 = !{!"short", !5, i64 0}
+  !5 = !{!"omnipotent char", !6, i64 0}
+  !6 = !{!"Simple C/C++ TBAA"}
+
+...
+---
+name:            copy
+alignment:       1
+exposesReturnsTwice: false
+legalized:       false
+regBankSelected: false
+selected:        false
+failedISel:      false
+tracksRegLiveness: false
+hasWinCFI:       false
+registers:       []
+liveins:         
+  - { reg: '$r0', virtual-reg: '' }
+  - { reg: '$r1', virtual-reg: '' }
+  - { reg: '$r2', virtual-reg: '' }
+frameInfo:       
+  isFrameAddressTaken: false
+  isReturnAddressTaken: false
+  hasStackMap:     false
+  hasPatchPoint:   false
+  stackSize:       8
+  offsetAdjustment: 0
+  maxAlignment:    4
+  adjustsStack:    false
+  hasCalls:        false
+  stackProtector:  ''
+  maxCallFrameSize: 0
+  cvBytesOfCalleeSavedRegisters: 0
+  hasOpaqueSPAdjustment: false
+  hasVAStart:      false
+  hasMustTailInVarArgFunc: false
+  localFrameSize:  0
+  savePoint:       ''
+  restorePoint:    ''
+fixedStack:      []
+stack:           
+  - { id: 0, name: '', type: spill-slot, offset: -4, size: 4, alignment: 4, 
+      stack-id: default, callee-saved-register: '$lr', callee-saved-restored: false, 
+      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
+  - { id: 1, name: '', type: spill-slot, offset: -8, size: 4, alignment: 4, 
+      stack-id: default, callee-saved-register: '$r7', callee-saved-restored: true, 
+      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
+constants:       []
+machineFunctionInfo: {}
+body:             |
+  bb.0.entry:
+    successors: %bb.1(0x40000000), %bb.3(0x40000000)
+  
+    frame-setup tPUSH 14, $noreg, $r7, killed $lr, implicit-def $sp, implicit $sp
+    frame-setup CFI_INSTRUCTION def_cfa_offset 8
+    frame-setup CFI_INSTRUCTION offset $lr, -4
+    frame-setup CFI_INSTRUCTION offset $r7, -8
+    $r7 = frame-setup tMOVr $sp, 14, $noreg
+    frame-setup CFI_INSTRUCTION def_cfa_register $r7
+    t2WhileLoopStart $r2, %bb.3
+    tB %bb.1, 14, $noreg
+  
+  bb.1.while.body.preheader:
+    successors: %bb.2(0x80000000)
+  
+    $lr = tMOVr killed $r2, 14, $noreg
+  
+  bb.2.while.body:
+    successors: %bb.2(0x7c000000), %bb.3(0x04000000)
+  
+    renamable $r2, renamable $r1 = t2LDRH_POST killed renamable $r1, 2, 14, $noreg :: (load 2 from %ir.b.addr.05, !tbaa !3)
+    early-clobber renamable $r0 = t2STRH_POST killed renamable $r2, killed renamable $r0, 2, 14, $noreg :: (store 2 into %ir.a.addr.06, !tbaa !3)
+    renamable $lr = t2LoopDec killed renamable $lr, 1
+    t2LoopEnd renamable $lr, %bb.2
+    tB %bb.3, 14, $noreg
+  
+  bb.3.while.end:
+    tPOP_RET 14, $noreg, def $r7, def $pc
+
+...