diff --git a/llvm/lib/CodeGen/HardwareLoops.cpp b/llvm/lib/CodeGen/HardwareLoops.cpp
--- a/llvm/lib/CodeGen/HardwareLoops.cpp
+++ b/llvm/lib/CodeGen/HardwareLoops.cpp
@@ -327,13 +327,16 @@
     return false;
   }
 
-  // Allow overriding of the counter width and loop decrement value.
-  if (Opts.Bitwidth.has_value()) {
-    HWLoopInfo.CountType = IntegerType::get(Ctx, Opts.Bitwidth.value());
+  // Handle the unexpected inputs.
+  if (!Opts.Bitwidth.has_value())
+    Opts.Bitwidth = 32;
+  if (!Opts.Decrement.has_value()) {
+    Opts.Decrement = 1;
   }
+  // Allow overriding of the counter width and loop decrement value.
+  HWLoopInfo.CountType = IntegerType::get(Ctx, Opts.Bitwidth.value());
 
-  if (Opts.Decrement.has_value())
-    HWLoopInfo.LoopDecrement =
+  HWLoopInfo.LoopDecrement =
       ConstantInt::get(HWLoopInfo.CountType, Opts.Decrement.value());
 
   MadeChange |= TryConvertLoop(HWLoopInfo);
@@ -389,8 +392,11 @@
     Value *EltsRem = InsertPHICounter(Setup, LoopDec);
     LoopDec->setOperand(0, EltsRem);
     UpdateBranch(LoopDec);
-  } else
+  } else {
+    if (!LoopDecrement) // LoopDecrement can not be nullptr!
+      return;
     InsertLoopDec();
+  }
 
   // Run through the basic blocks of the loop and see if any of them have dead
   // PHIs that can be removed.
diff --git a/llvm/test/Transforms/HardwareLoops/unexpected-inputs.ll b/llvm/test/Transforms/HardwareLoops/unexpected-inputs.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Transforms/HardwareLoops/unexpected-inputs.ll
@@ -0,0 +1,37 @@
+; RUN: opt -passes='hardware-loops<force-hardware-loops>' -S %s -o - | FileCheck %s --check-prefix=CHECK
+; RUN: opt -passes='hardware-loops<force-hardware-loops;hardware-loop-decrement=1>' -S %s -o - | FileCheck %s --check-prefix=CHECK
+; RUN: opt -passes='hardware-loops<force-hardware-loops;hardware-loop-counter-bitwidth=32>' -S %s -o - | FileCheck %s --check-prefix=CHECK
+
+define void @while_lt(i32 %i, i32 %N, ptr nocapture %A) {
+; CHECK-LABEL: @while_lt(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[CMP4:%.*]] = icmp ult i32 [[I:%.*]], [[N:%.*]]
+; CHECK-NEXT:    br i1 [[CMP4]], label [[WHILE_BODY_PREHEADER:%.*]], label [[WHILE_END:%.*]]
+; CHECK:       while.body.preheader:
+; CHECK-NEXT:    [[TMP0:%.*]] = sub i32 [[N]], [[I]]
+; CHECK-NEXT:    call void @llvm.set.loop.iterations.i32(i32 [[TMP0]])
+; CHECK-NEXT:    br label [[WHILE_BODY:%.*]]
+; CHECK:       while.body:
+; CHECK-NEXT:    [[I_ADDR_05:%.*]] = phi i32 [ [[INC:%.*]], [[WHILE_BODY]] ], [ [[I]], [[WHILE_BODY_PREHEADER]] ]
+; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds i32, ptr [[A:%.*]], i32 [[I_ADDR_05]]
+; CHECK-NEXT:    store i32 [[I_ADDR_05]], ptr [[ARRAYIDX]], align 4
+; CHECK-NEXT:    [[INC]] = add nuw i32 [[I_ADDR_05]], 1
+; CHECK-NEXT:    [[TMP1:%.*]] = call i1 @llvm.loop.decrement.i32(i32 1)
+; CHECK-NEXT:    br i1 [[TMP1]], label [[WHILE_BODY]], label [[WHILE_END]]
+; CHECK:       while.end:
+; CHECK-NEXT:    ret void
+entry:
+  %cmp4 = icmp ult i32 %i, %N
+  br i1 %cmp4, label %while.body, label %while.end
+
+while.body:
+  %i.addr.05 = phi i32 [ %inc, %while.body ], [ %i, %entry ]
+  %arrayidx = getelementptr inbounds i32, ptr %A, i32 %i.addr.05
+  store i32 %i.addr.05, ptr %arrayidx, align 4
+  %inc = add nuw i32 %i.addr.05, 1
+  %exitcond = icmp eq i32 %inc, %N
+  br i1 %exitcond, label %while.end, label %while.body
+
+while.end:
+  ret void
+}