diff --git a/llvm/include/llvm/Transforms/Scalar/LoopIdiomRecognize.h b/llvm/include/llvm/Transforms/Scalar/LoopIdiomRecognize.h
index 0c6406d861851..241a3fc109360 100644
--- a/llvm/include/llvm/Transforms/Scalar/LoopIdiomRecognize.h
+++ b/llvm/include/llvm/Transforms/Scalar/LoopIdiomRecognize.h
@@ -34,6 +34,12 @@ struct DisableLIRP {
 
   /// When true, Memcpy is disabled.
   static bool Memcpy;
+
+  /// When true, Strlen is disabled.
+  static bool Strlen;
+
+  /// When true, Wcslen is disabled.
+  static bool Wcslen;
 };
 
 /// Performs Loop Idiom Recognize Pass.
diff --git a/llvm/include/llvm/Transforms/Utils/BuildLibCalls.h b/llvm/include/llvm/Transforms/Utils/BuildLibCalls.h
index a8fb38e726004..50f695dbe6c07 100644
--- a/llvm/include/llvm/Transforms/Utils/BuildLibCalls.h
+++ b/llvm/include/llvm/Transforms/Utils/BuildLibCalls.h
@@ -93,6 +93,12 @@ namespace llvm {
   Value *emitStrLen(Value *Ptr, IRBuilderBase &B, const DataLayout &DL,
                     const TargetLibraryInfo *TLI);
 
+  /// Emit a call to the wcslen function to the builder, for the specified
+  /// pointer. Ptr is required to be some pointer type, and the return value has
+  /// 'size_t' type.
+  Value *emitWcsLen(Value *Ptr, IRBuilderBase &B, const DataLayout &DL,
+                    const TargetLibraryInfo *TLI);
+
   /// Emit a call to the strdup function to the builder, for the specified
   /// pointer. Ptr is required to be some pointer type, and the return value has
   /// 'i8*' type.
diff --git a/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp b/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
index 2462ec33e0c20..f90d7967cb577 100644
--- a/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
@@ -20,8 +20,7 @@
 //
 // TODO List:
 //
-// Future loop memory idioms to recognize:
-//   memcmp, strlen, etc.
+// Future loop memory idioms to recognize: memcmp, etc.
 //
 // This could recognize common matrix multiplies and dot product idioms and
 // replace them with calls to BLAS (if linked in??).
@@ -33,6 +32,7 @@
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/MapVector.h"
+#include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallVector.h"
@@ -97,6 +97,7 @@ using namespace llvm;
 STATISTIC(NumMemSet, "Number of memset's formed from loop stores");
 STATISTIC(NumMemCpy, "Number of memcpy's formed from loop load+stores");
 STATISTIC(NumMemMove, "Number of memmove's formed from loop load+stores");
+STATISTIC(NumStrLen, "Number of strlen's and wcslen's formed from loop loads");
 STATISTIC(
     NumShiftUntilBitTest,
     "Number of uncountable loops recognized as 'shift until bitttest' idiom");
@@ -126,6 +127,22 @@ static cl::opt<bool, true>
                       cl::location(DisableLIRP::Memcpy), cl::init(false),
                       cl::ReallyHidden);
 
+bool DisableLIRP::Strlen;
+static cl::opt<bool, true>
+    DisableLIRPStrlen("disable-loop-idiom-strlen",
+                      cl::desc("Proceed with loop idiom recognize pass, but do "
+                               "not convert loop(s) to strlen."),
+                      cl::location(DisableLIRP::Strlen), cl::init(false),
+                      cl::ReallyHidden);
+
+bool DisableLIRP::Wcslen;
+static cl::opt<bool, true>
+    EnableLIRPWcslen("disable-loop-idiom-wcslen",
+                     cl::desc("Proceed with loop idiom recognize pass, "
+                              "enable conversion of loop(s) to wcslen."),
+                     cl::location(DisableLIRP::Wcslen), cl::init(false),
+                     cl::ReallyHidden);
+
 static cl::opt<bool> UseLIRCodeSizeHeurs(
     "use-lir-code-size-heurs",
     cl::desc("Use loop idiom recognition code size heuristics when compiling "
@@ -246,6 +263,7 @@ class LoopIdiomRecognize {
 
   bool recognizeShiftUntilBitTest();
   bool recognizeShiftUntilZero();
+  bool recognizeAndInsertStrLen();
 
   /// @}
 };
@@ -1494,7 +1512,17 @@ bool LoopIdiomRecognize::runOnNoncountableLoop() {
 
   return recognizePopcount() || recognizeAndInsertFFS() ||
          recognizeShiftUntilBitTest() || recognizeShiftUntilZero() ||
-         recognizeShiftUntilLessThan();
+         recognizeShiftUntilLessThan() || recognizeAndInsertStrLen();
+}
+
+/// Check if a Value is either a nullptr or a constant int zero
+static bool isZeroConstant(const Value *Val) {
+  if (isa<ConstantPointerNull>(Val))
+    return true;
+  const ConstantInt *CmpZero = dyn_cast<ConstantInt>(Val);
+  if (!CmpZero || !CmpZero->isZero())
+    return false;
+  return true;
 }
 
 /// Check if the given conditional branch is based on the comparison between
@@ -1512,8 +1540,7 @@ static Value *matchCondition(BranchInst *BI, BasicBlock *LoopEntry,
   if (!Cond)
     return nullptr;
 
-  ConstantInt *CmpZero = dyn_cast<ConstantInt>(Cond->getOperand(1));
-  if (!CmpZero || !CmpZero->isZero())
+  if (!isZeroConstant(Cond->getOperand(1)))
     return nullptr;
 
   BasicBlock *TrueSucc = BI->getSuccessor(0);
@@ -1529,6 +1556,279 @@ static Value *matchCondition(BranchInst *BI, BasicBlock *LoopEntry,
   return nullptr;
 }
 
+namespace {
+
+class StrlenVerifier {
+public:
+  explicit StrlenVerifier(const Loop *CurLoop, ScalarEvolution *SE,
+                          const TargetLibraryInfo *TLI)
+      : CurLoop(CurLoop), SE(SE), TLI(TLI) {}
+
+  bool isValidStrlenIdiom() {
+    // Give up if the loop has multiple blocks, multiple backedges, or
+    // multiple exit blocks
+    if (CurLoop->getNumBackEdges() != 1 || CurLoop->getNumBlocks() != 1 ||
+        !CurLoop->getUniqueExitBlock())
+      return false;
+
+    // It should have a preheader and a branch instruction.
+    BasicBlock *Preheader = CurLoop->getLoopPreheader();
+    if (!Preheader)
+      return false;
+
+    BranchInst *EntryBI = dyn_cast<BranchInst>(Preheader->getTerminator());
+    if (!EntryBI)
+      return false;
+
+    // The loop exit must be conditioned on an icmp with 0 the null terminator.
+    // The icmp operand has to be a load on some SSA reg that increments
+    // by 1 in the loop.
+    BasicBlock *LoopBody = *CurLoop->block_begin();
+
+    // Skip if the body is too big as it most likely is not a strlen idiom.
+    if (!LoopBody || LoopBody->size() >= 15)
+      return false;
+
+    BranchInst *LoopTerm = dyn_cast<BranchInst>(LoopBody->getTerminator());
+    Value *LoopCond = matchCondition(LoopTerm, LoopBody);
+    if (!LoopCond)
+      return false;
+
+    LoadInst *LoopLoad = dyn_cast<LoadInst>(LoopCond);
+    if (!LoopLoad || LoopLoad->getPointerAddressSpace() != 0)
+      return false;
+
+    OperandType = LoopLoad->getType();
+    if (!OperandType || !OperandType->isIntegerTy())
+      return false;
+
+    // See if the pointer expression is an AddRec with constant step a of form
+    // ({n,+,a}) where a is the width of the char type.
+    Value *IncPtr = LoopLoad->getPointerOperand();
+    const SCEVAddRecExpr *LoadEv =
+        dyn_cast<SCEVAddRecExpr>(SE->getSCEV(IncPtr));
+    if (!LoadEv || LoadEv->getLoop() != CurLoop || !LoadEv->isAffine())
+      return false;
+    LoadBaseEv = LoadEv->getStart();
+
+    LLVM_DEBUG({
+      dbgs() << "pointer load scev: ";
+      LoadEv->print(outs());
+      dbgs() << "\n";
+    });
+
+    const SCEVConstant *Step =
+        dyn_cast<SCEVConstant>(LoadEv->getStepRecurrence(*SE));
+    if (!Step)
+      return false;
+
+    unsigned StepSize = 0;
+    StepSizeCI = dyn_cast<ConstantInt>(Step->getValue());
+    if (!StepSizeCI)
+      return false;
+    StepSize = StepSizeCI->getZExtValue();
+
+    // Verify that StepSize is consistent with platform char width.
+    OpWidth = OperandType->getIntegerBitWidth();
+    unsigned WcharSize = TLI->getWCharSize(*LoopLoad->getModule());
+    if (OpWidth != StepSize * 8)
+      return false;
+    if (OpWidth != 8 && OpWidth != 16 && OpWidth != 32)
+      return false;
+    if (OpWidth >= 16)
+      if (OpWidth != WcharSize * 8)
+        return false;
+
+    // Scan every instruction in the loop to ensure there are no side effects.
+    for (Instruction &I : *LoopBody)
+      if (I.mayHaveSideEffects())
+        return false;
+
+    BasicBlock *LoopExitBB = CurLoop->getExitBlock();
+    if (!LoopExitBB)
+      return false;
+
+    for (PHINode &PN : LoopExitBB->phis()) {
+      if (!SE->isSCEVable(PN.getType()))
+        return false;
+
+      const SCEV *Ev = SE->getSCEV(&PN);
+      if (!Ev)
+        return false;
+
+      LLVM_DEBUG({
+        dbgs() << "loop exit phi scev: ";
+        Ev->print(dbgs());
+        dbgs() << "\n";
+      });
+
+      // Since we verified that the loop trip count will be a valid strlen
+      // idiom, we can expand all lcssa phi with {n,+,1} as (n + strlen) and use
+      // SCEVExpander materialize the loop output.
+      const SCEVAddRecExpr *AddRecEv = dyn_cast<SCEVAddRecExpr>(Ev);
+      if (!AddRecEv || !AddRecEv->isAffine())
+        return false;
+
+      // We only want RecAddExpr with recurrence step that is constant. This
+      // is good enough for all the idioms we want to recognize. Later we expand
+      // and materialize the recurrence as {base,+,a} -> (base + a * strlen)
+      if (!dyn_cast<SCEVConstant>(AddRecEv->getStepRecurrence(*SE)))
+        return false;
+    }
+
+    return true;
+  }
+
+public:
+  const Loop *CurLoop;
+  ScalarEvolution *SE;
+  const TargetLibraryInfo *TLI;
+
+  unsigned OpWidth;
+  ConstantInt *StepSizeCI;
+  const SCEV *LoadBaseEv;
+  Type *OperandType;
+};
+
+} // namespace
+
+/// The Strlen Idiom we are trying to detect has the following structure
+///
+/// preheader:
+///   ...
+///   br label %body, ...
+///
+/// body:
+///   ... ; %0 is incremented by a gep
+///   %1 = load i8, ptr %0, align 1
+///   %2 = icmp eq i8 %1, 0
+///   br i1 %2, label %exit, label %body
+///
+/// exit:
+///   %lcssa = phi [%0, %body], ...
+///
+/// We expect the strlen idiom to have a load of a character type that
+/// is compared against '\0', and such load pointer operand must have scev
+/// expression of the form {%str,+,c} where c is a ConstantInt of the
+/// appropiate character width for the idiom, and %str is the base of the string
+/// And, that all lcssa phis have the form {...,+,n} where n is a constant,
+///
+/// When transforming the output of the strlen idiom, the lccsa phi are
+/// expanded using SCEVExpander as {base scev,+,a} -> (base scev + a * strlen)
+/// and all subsequent uses are replaced. For example,
+///
+/// \code{.c}
+///     const char* base = str;
+///     while (*str != '\0')
+///         ++str;
+///     size_t result = str - base;
+/// \endcode
+///
+/// will be transformed as follows: The idiom will be replaced by a strlen
+/// computation to compute the address of the null terminator of the string.
+///
+/// \code{.c}
+///     const char* base = str;
+///     const char* end = base + strlen(str);
+///     size_t result = end - base;
+/// \endcode
+///
+/// In the case we index by an induction variable, as long as the induction
+/// variable has a constant int increment, we can replace all such indvars
+/// with the closed form computation of strlen
+///
+/// \code{.c}
+///     size_t i = 0;
+///     while (str[i] != '\0')
+///         ++i;
+///     size_t result = i;
+/// \endcode
+///
+/// Will be replaced by
+///
+/// \code{.c}
+///     size_t i = 0 + strlen(str);
+///     size_t result = i;
+/// \endcode
+///
+bool LoopIdiomRecognize::recognizeAndInsertStrLen() {
+  if (DisableLIRP::All)
+    return false;
+
+  StrlenVerifier Verifier(CurLoop, SE, TLI);
+
+  if (!Verifier.isValidStrlenIdiom())
+    return false;
+
+  BasicBlock *Preheader = CurLoop->getLoopPreheader();
+  BasicBlock *LoopExitBB = CurLoop->getExitBlock();
+
+  IRBuilder<> Builder(Preheader->getTerminator());
+  SCEVExpander Expander(*SE, Preheader->getModule()->getDataLayout(),
+                        "strlen_idiom");
+  Value *MaterialzedBase = Expander.expandCodeFor(
+      Verifier.LoadBaseEv, Verifier.LoadBaseEv->getType(),
+      Builder.GetInsertPoint());
+
+  Value *StrLenFunc = nullptr;
+  if (Verifier.OpWidth == 8) {
+    if (DisableLIRP::Strlen)
+      return false;
+    if (!isLibFuncEmittable(Preheader->getModule(), TLI, LibFunc_strlen))
+      return false;
+    StrLenFunc = emitStrLen(MaterialzedBase, Builder, *DL, TLI);
+  } else {
+    if (DisableLIRP::Wcslen)
+      return false;
+    if (!isLibFuncEmittable(Preheader->getModule(), TLI, LibFunc_wcslen))
+      return false;
+    StrLenFunc = emitWcsLen(MaterialzedBase, Builder, *DL, TLI);
+  }
+  assert(StrLenFunc && "Failed to emit strlen function.");
+
+  const SCEV *StrlenEv = SE->getSCEV(StrLenFunc);
+  SmallVector<PHINode *, 4> Cleanup;
+  for (PHINode &PN : LoopExitBB->phis()) {
+    // We can now materialize the loop output as all phi have scev {base,+,a}.
+    // We expand the phi as:
+    //   %strlen = call i64 @strlen(%str)
+    //   %phi.new = base expression + step * %strlen
+    const SCEV *Ev = SE->getSCEV(&PN);
+    const SCEVAddRecExpr *AddRecEv = dyn_cast<SCEVAddRecExpr>(Ev);
+    const SCEVConstant *Step =
+        dyn_cast<SCEVConstant>(AddRecEv->getStepRecurrence(*SE));
+    const SCEV *Base = AddRecEv->getStart();
+
+    // It is safe to truncate to base since if base is narrower than size_t
+    // the equivalent user code will have to truncate anyways.
+    const SCEV *NewEv = SE->getAddExpr(
+        Base, SE->getMulExpr(Step, SE->getTruncateOrSignExtend(
+                                       StrlenEv, Base->getType())));
+
+    Value *MaterializedPHI = Expander.expandCodeFor(NewEv, NewEv->getType(),
+                                                    Builder.GetInsertPoint());
+    Expander.clear();
+    PN.replaceAllUsesWith(MaterializedPHI);
+    Cleanup.push_back(&PN);
+  }
+
+  // All LCSSA Loop Phi are dead, the left over dead loop body can be cleaned
+  // up by later passes
+  for (PHINode *PN : Cleanup)
+    RecursivelyDeleteDeadPHINode(PN);
+  SE->forgetLoop(CurLoop);
+
+  ++NumStrLen;
+  LLVM_DEBUG(dbgs() << "  Formed strlen idiom: " << *StrLenFunc << "\n");
+  ORE.emit([&]() {
+    return OptimizationRemark(DEBUG_TYPE, "recognizeAndInsertStrLen",
+                              CurLoop->getStartLoc(), Preheader)
+           << "Transformed " << StrLenFunc->getName() << " loop idiom";
+  });
+
+  return true;
+}
+
 /// Check if the given conditional branch is based on an unsigned less-than
 /// comparison between a variable and a constant, and if the comparison is false
 /// the control yields to the loop entry. If the branch matches the behaviour,
diff --git a/llvm/lib/Transforms/Utils/BuildLibCalls.cpp b/llvm/lib/Transforms/Utils/BuildLibCalls.cpp
index 2301be6977cef..24eefc91117b4 100644
--- a/llvm/lib/Transforms/Utils/BuildLibCalls.cpp
+++ b/llvm/lib/Transforms/Utils/BuildLibCalls.cpp
@@ -1582,6 +1582,15 @@ Value *llvm::emitStrLen(Value *Ptr, IRBuilderBase &B, const DataLayout &DL,
   return emitLibCall(LibFunc_strlen, SizeTTy, CharPtrTy, Ptr, B, TLI);
 }
 
+Value *llvm::emitWcsLen(Value *Ptr, IRBuilderBase &B, const DataLayout &DL,
+                        const TargetLibraryInfo *TLI) {
+  assert(Ptr && Ptr->getType()->isPointerTy() &&
+         "Argument to wcslen intrinsic must be a pointer.");
+  Type *PtrTy = B.getPtrTy();
+  Type *SizeTTy = getSizeTTy(B, TLI);
+  return emitLibCall(LibFunc_wcslen, SizeTTy, PtrTy, Ptr, B, TLI);
+}
+
 Value *llvm::emitStrDup(Value *Ptr, IRBuilderBase &B,
                         const TargetLibraryInfo *TLI) {
   Type *CharPtrTy = B.getPtrTy();
diff --git a/llvm/test/Transforms/LoopIdiom/strlen-not-emittable.ll b/llvm/test/Transforms/LoopIdiom/strlen-not-emittable.ll
new file mode 100644
index 0000000000000..0be76cbd42a72
--- /dev/null
+++ b/llvm/test/Transforms/LoopIdiom/strlen-not-emittable.ll
@@ -0,0 +1,66 @@
+; RUN: opt -passes='loop(loop-idiom),verify' < %s -S | FileCheck %s
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; invalid libcall prototype
+declare void @strlen(i32)
+declare void @wcslen(i32)
+
+define i64 @valid_wcslen32(ptr %src) {
+; CHECK-LABEL: valid_wcslen32
+; CHECK-NOT: call {{.*}} @wcslen
+entry:
+  %cmp = icmp eq ptr %src, null
+  br i1 %cmp, label %return, label %lor.lhs.false
+
+lor.lhs.false:                                    ; preds = %entry
+  %0 = load i32, ptr %src, align 4
+  %cmp1 = icmp eq i32 %0, 0
+  br i1 %cmp1, label %return, label %while.cond.preheader
+
+while.cond.preheader:                             ; preds = %lor.lhs.false
+  br label %while.cond
+
+while.cond:                                       ; preds = %while.cond.preheader, %while.cond
+  %src.pn = phi ptr [ %curr.0, %while.cond ], [ %src, %while.cond.preheader ]
+  %curr.0 = getelementptr inbounds i8, ptr %src.pn, i64 4
+  %1 = load i32, ptr %curr.0, align 4
+  %tobool.not = icmp eq i32 %1, 0
+  br i1 %tobool.not, label %while.end, label %while.cond
+
+while.end:                                        ; preds = %while.cond
+  %curr.0.lcssa = phi ptr [ %curr.0, %while.cond ]
+  %sub.ptr.lhs.cast = ptrtoint ptr %curr.0.lcssa to i64
+  %sub.ptr.rhs.cast = ptrtoint ptr %src to i64
+  %sub.ptr.sub = sub i64 %sub.ptr.lhs.cast, %sub.ptr.rhs.cast
+  %sub.ptr.div = ashr exact i64 %sub.ptr.sub, 2
+  br label %return
+
+return:                                           ; preds = %entry, %lor.lhs.false, %while.end
+  %retval.0 = phi i64 [ %sub.ptr.div, %while.end ], [ 0, %lor.lhs.false ], [ 0, %entry ]
+  ret i64 %retval.0
+}
+
+define i64 @valid_strlen(ptr %str) {
+; CHECK-LABEL: valid_strlen
+; CHECK-NOT: call {{.*}} @strlen
+entry:
+  br label %while.cond
+
+while.cond:
+  %str.addr.0 = phi ptr [ %str, %entry ], [ %incdec.ptr, %while.cond ]
+  %0 = load i8, ptr %str.addr.0, align 1
+  %cmp.not = icmp eq i8 %0, 0
+  %incdec.ptr = getelementptr i8, ptr %str.addr.0, i64 1
+  br i1 %cmp.not, label %while.end, label %while.cond
+
+while.end:
+  %sub.ptr.lhs.cast = ptrtoint ptr %str.addr.0 to i64
+  %sub.ptr.rhs.cast = ptrtoint ptr %str to i64
+  %sub.ptr.sub = sub i64 %sub.ptr.lhs.cast, %sub.ptr.rhs.cast
+  ret i64 %sub.ptr.sub
+}
+
+!llvm.module.flags = !{!0}
+!0 = !{i32 1, !"wchar_size", i32 4}
diff --git a/llvm/test/Transforms/LoopIdiom/strlen.ll b/llvm/test/Transforms/LoopIdiom/strlen.ll
new file mode 100644
index 0000000000000..137a17f541cd4
--- /dev/null
+++ b/llvm/test/Transforms/LoopIdiom/strlen.ll
@@ -0,0 +1,614 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -passes='loop(loop-idiom),verify' < %s -S | FileCheck %s
+
+declare void @other()
+declare void @use(ptr)
+declare void @usei(i32)
+declare void @usel(i64)
+
+; size_t basic_strlen(const char* str) {
+;     while (*str != '\0') {
+;         ++str;
+;     }
+;     return str - base;
+; }
+define i64 @valid_basic_strlen(ptr %str) {
+; CHECK-LABEL: define i64 @valid_basic_strlen(
+; CHECK-SAME: ptr [[STR:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*]]:
+; CHECK-NEXT:    [[STRLEN:%.*]] = call i64 @strlen(ptr [[STR]])
+; CHECK-NEXT:    [[SCEVGEP:%.*]] = getelementptr i8, ptr [[STR]], i64 [[STRLEN]]
+; CHECK-NEXT:    br label %[[WHILE_COND:.*]]
+; CHECK:       [[WHILE_COND]]:
+; CHECK-NEXT:    [[STR_ADDR_0:%.*]] = phi ptr [ [[STR]], %[[ENTRY]] ], [ [[INCDEC_PTR:%.*]], %[[WHILE_COND]] ]
+; CHECK-NEXT:    [[TMP0:%.*]] = load i8, ptr [[STR_ADDR_0]], align 1
+; CHECK-NEXT:    [[CMP_NOT:%.*]] = icmp eq i8 [[TMP0]], 0
+; CHECK-NEXT:    [[INCDEC_PTR]] = getelementptr i8, ptr [[STR_ADDR_0]], i64 1
+; CHECK-NEXT:    br i1 [[CMP_NOT]], label %[[WHILE_END:.*]], label %[[WHILE_COND]]
+; CHECK:       [[WHILE_END]]:
+; CHECK-NEXT:    [[SUB_PTR_LHS_CAST:%.*]] = ptrtoint ptr [[SCEVGEP]] to i64
+; CHECK-NEXT:    [[SUB_PTR_RHS_CAST:%.*]] = ptrtoint ptr [[STR]] to i64
+; CHECK-NEXT:    [[SUB_PTR_SUB:%.*]] = sub i64 [[SUB_PTR_LHS_CAST]], [[SUB_PTR_RHS_CAST]]
+; CHECK-NEXT:    ret i64 [[SUB_PTR_SUB]]
+;
+entry:
+  br label %while.cond
+
+while.cond:
+  %str.addr.0 = phi ptr [ %str, %entry ], [ %incdec.ptr, %while.cond ]
+  %0 = load i8, ptr %str.addr.0, align 1
+  %cmp.not = icmp eq i8 %0, 0
+  %incdec.ptr = getelementptr i8, ptr %str.addr.0, i64 1
+  br i1 %cmp.not, label %while.end, label %while.cond
+
+while.end:
+  %sub.ptr.lhs.cast = ptrtoint ptr %str.addr.0 to i64
+  %sub.ptr.rhs.cast = ptrtoint ptr %str to i64
+  %sub.ptr.sub = sub i64 %sub.ptr.lhs.cast, %sub.ptr.rhs.cast
+  ret i64 %sub.ptr.sub
+}
+
+; int valid_basic_strlen_rotated(const char* str) {
+;     const char* base = str;
+;     if (!*str) return 0;
+;     do {
+;         ++str;
+;     } while (*str);
+;     return str - base;
+; }
+define i32 @valid_basic_strlen_rotated(ptr %str) {
+; CHECK-LABEL: define i32 @valid_basic_strlen_rotated(
+; CHECK-SAME: ptr [[STR:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*]]:
+; CHECK-NEXT:    [[TMP0:%.*]] = load i8, ptr [[STR]], align 1
+; CHECK-NEXT:    [[TOBOOL_NOT:%.*]] = icmp eq i8 [[TMP0]], 0
+; CHECK-NEXT:    br i1 [[TOBOOL_NOT]], label %[[CLEANUP:.*]], label %[[DO_BODY_PREHEADER:.*]]
+; CHECK:       [[DO_BODY_PREHEADER]]:
+; CHECK-NEXT:    [[SCEVGEP:%.*]] = getelementptr i8, ptr [[STR]], i64 1
+; CHECK-NEXT:    [[STRLEN:%.*]] = call i64 @strlen(ptr [[SCEVGEP]])
+; CHECK-NEXT:    [[TMP1:%.*]] = add i64 [[STRLEN]], 1
+; CHECK-NEXT:    [[SCEVGEP1:%.*]] = getelementptr i8, ptr [[STR]], i64 [[TMP1]]
+; CHECK-NEXT:    br label %[[DO_BODY:.*]]
+; CHECK:       [[DO_BODY]]:
+; CHECK-NEXT:    [[STR_ADDR_0:%.*]] = phi ptr [ [[INCDEC_PTR:%.*]], %[[DO_BODY]] ], [ [[STR]], %[[DO_BODY_PREHEADER]] ]
+; CHECK-NEXT:    [[INCDEC_PTR]] = getelementptr inbounds nuw i8, ptr [[STR_ADDR_0]], i64 1
+; CHECK-NEXT:    [[TMP2:%.*]] = load i8, ptr [[INCDEC_PTR]], align 1
+; CHECK-NEXT:    [[TOBOOL1_NOT:%.*]] = icmp eq i8 [[TMP2]], 0
+; CHECK-NEXT:    br i1 [[TOBOOL1_NOT]], label %[[DO_END:.*]], label %[[DO_BODY]]
+; CHECK:       [[DO_END]]:
+; CHECK-NEXT:    [[SUB_PTR_LHS_CAST:%.*]] = ptrtoint ptr [[SCEVGEP1]] to i64
+; CHECK-NEXT:    [[SUB_PTR_RHS_CAST:%.*]] = ptrtoint ptr [[STR]] to i64
+; CHECK-NEXT:    [[SUB_PTR_SUB:%.*]] = sub i64 [[SUB_PTR_LHS_CAST]], [[SUB_PTR_RHS_CAST]]
+; CHECK-NEXT:    [[CONV:%.*]] = trunc i64 [[SUB_PTR_SUB]] to i32
+; CHECK-NEXT:    br label %[[CLEANUP]]
+; CHECK:       [[CLEANUP]]:
+; CHECK-NEXT:    [[RETVAL_0:%.*]] = phi i32 [ [[CONV]], %[[DO_END]] ], [ 0, %[[ENTRY]] ]
+; CHECK-NEXT:    ret i32 [[RETVAL_0]]
+;
+entry:
+  %0 = load i8, ptr %str, align 1
+  %tobool.not = icmp eq i8 %0, 0
+  br i1 %tobool.not, label %cleanup, label %do.body
+
+do.body:
+  %str.addr.0 = phi ptr [ %incdec.ptr, %do.body ], [ %str, %entry ]
+  %incdec.ptr = getelementptr inbounds nuw i8, ptr %str.addr.0, i64 1
+  %1 = load i8, ptr %incdec.ptr, align 1
+  %tobool1.not = icmp eq i8 %1, 0
+  br i1 %tobool1.not, label %do.end, label %do.body
+
+do.end:
+  %sub.ptr.lhs.cast = ptrtoint ptr %incdec.ptr to i64
+  %sub.ptr.rhs.cast = ptrtoint ptr %str to i64
+  %sub.ptr.sub = sub i64 %sub.ptr.lhs.cast, %sub.ptr.rhs.cast
+  %conv = trunc i64 %sub.ptr.sub to i32
+  br label %cleanup
+
+cleanup:
+  %retval.0 = phi i32 [ %conv, %do.end ], [ 0, %entry ]
+  ret i32 %retval.0
+}
+
+; int valid_strlen_with_aux_indvar(const char* str) {
+;   int count = 0;
+;   int count_offset = -10;
+;   int count_multiple = 0;
+;
+;   while (*str) {
+;     ++str;
+;     ++count;
+;     ++count_offset;
+;     count_multiple += 2;
+;     ++foo;
+;   }
+;
+;   usei(count);
+;   usei(count_offset);
+;   usei(count_multiple);
+;   use(str);
+;   use(foo);
+; }
+define dso_local void @valid_strlen_with_aux_indvar(ptr noundef %str, ptr noundef %foo) local_unnamed_addr {
+; CHECK-LABEL: define dso_local void @valid_strlen_with_aux_indvar(
+; CHECK-SAME: ptr noundef [[STR:%.*]], ptr noundef [[FOO:%.*]]) local_unnamed_addr {
+; CHECK-NEXT:  [[ENTRY:.*]]:
+; CHECK-NEXT:    [[TMP0:%.*]] = load i8, ptr [[STR]], align 1
+; CHECK-NEXT:    [[TOBOOL_NOT9:%.*]] = icmp eq i8 [[TMP0]], 0
+; CHECK-NEXT:    br i1 [[TOBOOL_NOT9]], label %[[WHILE_END:.*]], label %[[WHILE_BODY_PREHEADER:.*]]
+; CHECK:       [[WHILE_BODY_PREHEADER]]:
+; CHECK-NEXT:    [[SCEVGEP:%.*]] = getelementptr i8, ptr [[STR]], i64 1
+; CHECK-NEXT:    [[STRLEN:%.*]] = call i64 @strlen(ptr [[SCEVGEP]])
+; CHECK-NEXT:    [[TMP1:%.*]] = add i64 [[STRLEN]], 1
+; CHECK-NEXT:    [[SCEVGEP1:%.*]] = getelementptr i8, ptr [[STR]], i64 [[TMP1]]
+; CHECK-NEXT:    [[TMP2:%.*]] = trunc i64 [[STRLEN]] to i32
+; CHECK-NEXT:    [[TMP3:%.*]] = add i32 [[TMP2]], 1
+; CHECK-NEXT:    [[TMP4:%.*]] = trunc i64 [[STRLEN]] to i32
+; CHECK-NEXT:    [[TMP5:%.*]] = add i32 [[TMP4]], -9
+; CHECK-NEXT:    [[TMP6:%.*]] = trunc i64 [[STRLEN]] to i32
+; CHECK-NEXT:    [[TMP7:%.*]] = shl i32 [[TMP6]], 1
+; CHECK-NEXT:    [[TMP8:%.*]] = add i32 [[TMP7]], 2
+; CHECK-NEXT:    [[TMP9:%.*]] = add i64 [[STRLEN]], 1
+; CHECK-NEXT:    [[SCEVGEP2:%.*]] = getelementptr i8, ptr [[FOO]], i64 [[TMP9]]
+; CHECK-NEXT:    br label %[[WHILE_BODY:.*]]
+; CHECK:       [[WHILE_BODY]]:
+; CHECK-NEXT:    [[COUNT_MULTIPLE_014:%.*]] = phi i32 [ [[ADD:%.*]], %[[WHILE_BODY]] ], [ 0, %[[WHILE_BODY_PREHEADER]] ]
+; CHECK-NEXT:    [[COUNT_OFFSET_013:%.*]] = phi i32 [ [[INC1:%.*]], %[[WHILE_BODY]] ], [ -10, %[[WHILE_BODY_PREHEADER]] ]
+; CHECK-NEXT:    [[COUNT_012:%.*]] = phi i32 [ [[INC:%.*]], %[[WHILE_BODY]] ], [ 0, %[[WHILE_BODY_PREHEADER]] ]
+; CHECK-NEXT:    [[FOO_ADDR_011:%.*]] = phi ptr [ [[INCDEC_PTR2:%.*]], %[[WHILE_BODY]] ], [ [[FOO]], %[[WHILE_BODY_PREHEADER]] ]
+; CHECK-NEXT:    [[STR_ADDR_010:%.*]] = phi ptr [ [[INCDEC_PTR:%.*]], %[[WHILE_BODY]] ], [ [[STR]], %[[WHILE_BODY_PREHEADER]] ]
+; CHECK-NEXT:    [[INCDEC_PTR]] = getelementptr inbounds nuw i8, ptr [[STR_ADDR_010]], i64 1
+; CHECK-NEXT:    [[INC]] = add nuw nsw i32 [[COUNT_012]], 1
+; CHECK-NEXT:    [[INC1]] = add nsw i32 [[COUNT_OFFSET_013]], 1
+; CHECK-NEXT:    [[ADD]] = add nuw nsw i32 [[COUNT_MULTIPLE_014]], 2
+; CHECK-NEXT:    [[INCDEC_PTR2]] = getelementptr inbounds nuw i8, ptr [[FOO_ADDR_011]], i64 1
+; CHECK-NEXT:    [[TMP10:%.*]] = load i8, ptr [[INCDEC_PTR]], align 1
+; CHECK-NEXT:    [[TOBOOL_NOT:%.*]] = icmp eq i8 [[TMP10]], 0
+; CHECK-NEXT:    br i1 [[TOBOOL_NOT]], label %[[WHILE_END_LOOPEXIT:.*]], label %[[WHILE_BODY]]
+; CHECK:       [[WHILE_END_LOOPEXIT]]:
+; CHECK-NEXT:    br label %[[WHILE_END]]
+; CHECK:       [[WHILE_END]]:
+; CHECK-NEXT:    [[STR_ADDR_0_LCSSA:%.*]] = phi ptr [ [[STR]], %[[ENTRY]] ], [ [[SCEVGEP1]], %[[WHILE_END_LOOPEXIT]] ]
+; CHECK-NEXT:    [[FOO_ADDR_0_LCSSA:%.*]] = phi ptr [ [[FOO]], %[[ENTRY]] ], [ [[SCEVGEP2]], %[[WHILE_END_LOOPEXIT]] ]
+; CHECK-NEXT:    [[COUNT_0_LCSSA:%.*]] = phi i32 [ 0, %[[ENTRY]] ], [ [[TMP3]], %[[WHILE_END_LOOPEXIT]] ]
+; CHECK-NEXT:    [[COUNT_OFFSET_0_LCSSA:%.*]] = phi i32 [ -10, %[[ENTRY]] ], [ [[TMP5]], %[[WHILE_END_LOOPEXIT]] ]
+; CHECK-NEXT:    [[COUNT_MULTIPLE_0_LCSSA:%.*]] = phi i32 [ 0, %[[ENTRY]] ], [ [[TMP8]], %[[WHILE_END_LOOPEXIT]] ]
+; CHECK-NEXT:    tail call void @usei(i32 noundef [[COUNT_0_LCSSA]])
+; CHECK-NEXT:    tail call void @usei(i32 noundef [[COUNT_OFFSET_0_LCSSA]])
+; CHECK-NEXT:    tail call void @usei(i32 noundef [[COUNT_MULTIPLE_0_LCSSA]])
+; CHECK-NEXT:    tail call void @use(ptr noundef nonnull [[STR_ADDR_0_LCSSA]])
+; CHECK-NEXT:    tail call void @use(ptr noundef [[FOO_ADDR_0_LCSSA]])
+; CHECK-NEXT:    ret void
+;
+entry:
+  %0 = load i8, ptr %str, align 1
+  %tobool.not9 = icmp eq i8 %0, 0
+  br i1 %tobool.not9, label %while.end, label %while.body
+
+while.body:
+  %count_multiple.014 = phi i32 [ %add, %while.body ], [ 0, %entry ]
+  %count_offset.013 = phi i32 [ %inc1, %while.body ], [ -10, %entry ]
+  %count.012 = phi i32 [ %inc, %while.body ], [ 0, %entry ]
+  %foo.addr.011 = phi ptr [ %incdec.ptr2, %while.body ], [ %foo, %entry ]
+  %str.addr.010 = phi ptr [ %incdec.ptr, %while.body ], [ %str, %entry ]
+  %incdec.ptr = getelementptr inbounds nuw i8, ptr %str.addr.010, i64 1
+  %inc = add nuw nsw i32 %count.012, 1
+  %inc1 = add nsw i32 %count_offset.013, 1
+  %add = add nuw nsw i32 %count_multiple.014, 2
+  %incdec.ptr2 = getelementptr inbounds nuw i8, ptr %foo.addr.011, i64 1
+  %1 = load i8, ptr %incdec.ptr, align 1
+  %tobool.not = icmp eq i8 %1, 0
+  br i1 %tobool.not, label %while.end, label %while.body
+
+while.end:
+  %str.addr.0.lcssa = phi ptr [ %str, %entry ], [ %incdec.ptr, %while.body ]
+  %foo.addr.0.lcssa = phi ptr [ %foo, %entry ], [ %incdec.ptr2, %while.body ]
+  %count.0.lcssa = phi i32 [ 0, %entry ], [ %inc, %while.body ]
+  %count_offset.0.lcssa = phi i32 [ -10, %entry ], [ %inc1, %while.body ]
+  %count_multiple.0.lcssa = phi i32 [ 0, %entry ], [ %add, %while.body ]
+  tail call void @usei(i32 noundef %count.0.lcssa) #3
+  tail call void @usei(i32 noundef %count_offset.0.lcssa) #3
+  tail call void @usei(i32 noundef %count_multiple.0.lcssa) #3
+  tail call void @use(ptr noundef nonnull %str.addr.0.lcssa) #3
+  tail call void @use(ptr noundef %foo.addr.0.lcssa) #3
+  ret void
+}
+
+; int valid_strlen_index(const char* str) {
+;     int i = 0;
+;     while (str[i]) {
+;         ++i;
+;     }
+;     return i;
+; }
+define i32 @valid_strlen_index(ptr %str) {
+; CHECK-LABEL: define i32 @valid_strlen_index(
+; CHECK-SAME: ptr [[STR:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*]]:
+; CHECK-NEXT:    [[STRLEN:%.*]] = call i64 @strlen(ptr [[STR]])
+; CHECK-NEXT:    br label %[[WHILE_COND:.*]]
+; CHECK:       [[WHILE_COND]]:
+; CHECK-NEXT:    [[INDVARS_IV:%.*]] = phi i64 [ [[INDVARS_IV_NEXT:%.*]], %[[WHILE_COND]] ], [ 0, %[[ENTRY]] ]
+; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds i8, ptr [[STR]], i64 [[INDVARS_IV]]
+; CHECK-NEXT:    [[TMP0:%.*]] = load i8, ptr [[ARRAYIDX]], align 1
+; CHECK-NEXT:    [[TOBOOL_NOT:%.*]] = icmp eq i8 [[TMP0]], 0
+; CHECK-NEXT:    [[INDVARS_IV_NEXT]] = add nuw nsw i64 [[INDVARS_IV]], 1
+; CHECK-NEXT:    br i1 [[TOBOOL_NOT]], label %[[WHILE_END:.*]], label %[[WHILE_COND]]
+; CHECK:       [[WHILE_END]]:
+; CHECK-NEXT:    [[TMP1:%.*]] = trunc nuw nsw i64 [[STRLEN]] to i32
+; CHECK-NEXT:    ret i32 [[TMP1]]
+;
+entry:
+  br label %while.cond
+
+while.cond:
+  %indvars.iv = phi i64 [ %indvars.iv.next, %while.cond ], [ 0, %entry ]
+  %arrayidx = getelementptr inbounds i8, ptr %str, i64 %indvars.iv
+  %0 = load i8, ptr %arrayidx, align 1
+  %tobool.not = icmp eq i8 %0, 0
+  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+  br i1 %tobool.not, label %while.end, label %while.cond
+
+while.end:
+  %1 = trunc nuw nsw i64 %indvars.iv to i32
+  ret i32 %1
+}
+
+; void valid_strlen_offset(const my_char* str) {
+;     if (*(str++) == '\0') return;
+;     if (*(str++) == '\0') return;
+;     if (*(str++) == '\0') return;
+;     while (*str) {
+;         ++str;
+;     }
+;     use(str);
+; }
+define dso_local void @valid_strlen_offset(ptr noundef %str) local_unnamed_addr {
+; CHECK-LABEL: define dso_local void @valid_strlen_offset(
+; CHECK-SAME: ptr noundef [[STR:%.*]]) local_unnamed_addr {
+; CHECK-NEXT:  [[ENTRY:.*:]]
+; CHECK-NEXT:    [[TMP0:%.*]] = load i8, ptr [[STR]], align 1
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i8 [[TMP0]], 0
+; CHECK-NEXT:    br i1 [[CMP]], label %[[RETURN:.*]], label %[[IF_END:.*]]
+; CHECK:       [[IF_END]]:
+; CHECK-NEXT:    [[INCDEC_PTR:%.*]] = getelementptr inbounds nuw i8, ptr [[STR]], i64 1
+; CHECK-NEXT:    [[TMP1:%.*]] = load i8, ptr [[INCDEC_PTR]], align 1
+; CHECK-NEXT:    [[CMP4:%.*]] = icmp eq i8 [[TMP1]], 0
+; CHECK-NEXT:    br i1 [[CMP4]], label %[[RETURN]], label %[[IF_END7:.*]]
+; CHECK:       [[IF_END7]]:
+; CHECK-NEXT:    [[INCDEC_PTR2:%.*]] = getelementptr inbounds nuw i8, ptr [[STR]], i64 2
+; CHECK-NEXT:    [[TMP2:%.*]] = load i8, ptr [[INCDEC_PTR2]], align 1
+; CHECK-NEXT:    [[CMP10:%.*]] = icmp eq i8 [[TMP2]], 0
+; CHECK-NEXT:    br i1 [[CMP10]], label %[[RETURN]], label %[[WHILE_COND_PREHEADER:.*]]
+; CHECK:       [[WHILE_COND_PREHEADER]]:
+; CHECK-NEXT:    [[INCDEC_PTR8:%.*]] = getelementptr i8, ptr [[STR]], i64 3
+; CHECK-NEXT:    [[STRLEN:%.*]] = call i64 @strlen(ptr [[INCDEC_PTR8]])
+; CHECK-NEXT:    [[TMP3:%.*]] = add i64 [[STRLEN]], 3
+; CHECK-NEXT:    [[SCEVGEP:%.*]] = getelementptr i8, ptr [[STR]], i64 [[TMP3]]
+; CHECK-NEXT:    br label %[[WHILE_COND:.*]]
+; CHECK:       [[WHILE_COND]]:
+; CHECK-NEXT:    [[STR_ADDR_0:%.*]] = phi ptr [ [[INCDEC_PTR14:%.*]], %[[WHILE_COND]] ], [ [[INCDEC_PTR8]], %[[WHILE_COND_PREHEADER]] ]
+; CHECK-NEXT:    [[TMP4:%.*]] = load i8, ptr [[STR_ADDR_0]], align 1
+; CHECK-NEXT:    [[TOBOOL_NOT:%.*]] = icmp eq i8 [[TMP4]], 0
+; CHECK-NEXT:    [[INCDEC_PTR14]] = getelementptr inbounds nuw i8, ptr [[STR_ADDR_0]], i64 1
+; CHECK-NEXT:    br i1 [[TOBOOL_NOT]], label %[[WHILE_END:.*]], label %[[WHILE_COND]]
+; CHECK:       [[WHILE_END]]:
+; CHECK-NEXT:    tail call void @use(ptr noundef nonnull [[SCEVGEP]])
+; CHECK-NEXT:    br label %[[RETURN]]
+; CHECK:       [[RETURN]]:
+; CHECK-NEXT:    ret void
+;
+entry:
+  %0 = load i8, ptr %str, align 1
+  %cmp = icmp eq i8 %0, 0
+  br i1 %cmp, label %return, label %if.end
+
+if.end:
+  %incdec.ptr = getelementptr inbounds nuw i8, ptr %str, i64 1
+  %1 = load i8, ptr %incdec.ptr, align 1
+  %cmp4 = icmp eq i8 %1, 0
+  br i1 %cmp4, label %return, label %if.end7
+
+if.end7:
+  %incdec.ptr2 = getelementptr inbounds nuw i8, ptr %str, i64 2
+  %2 = load i8, ptr %incdec.ptr2, align 1
+  %cmp10 = icmp eq i8 %2, 0
+  br i1 %cmp10, label %return, label %while.cond.preheader
+
+while.cond.preheader:
+  %incdec.ptr8 = getelementptr inbounds nuw i8, ptr %str, i64 3
+  br label %while.cond
+
+while.cond:
+  %str.addr.0 = phi ptr [ %incdec.ptr14, %while.cond ], [ %incdec.ptr8, %while.cond.preheader ]
+  %3 = load i8, ptr %str.addr.0, align 1
+  %tobool.not = icmp eq i8 %3, 0
+  %incdec.ptr14 = getelementptr inbounds nuw i8, ptr %str.addr.0, i64 1
+  br i1 %tobool.not, label %while.end, label %while.cond
+
+while.end:
+  tail call void @use(ptr noundef nonnull %str.addr.0) #3
+  br label %return
+
+return:
+  ret void
+}
+
+; void valid_nested_idiom(const char** strs, int n) {
+;     for (int i = 0; i < n; ++i) {
+;         const char* s = strs[i];
+;         int count = 0;
+;         while (*s) {
+;             ++s;
+;             ++count;
+;         }
+;         usei(count);
+;     }
+; }
+define void @valid_nested_idiom(ptr %strs, i32 %n) {
+; CHECK-LABEL: define void @valid_nested_idiom(
+; CHECK-SAME: ptr [[STRS:%.*]], i32 [[N:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*:]]
+; CHECK-NEXT:    [[CMP9:%.*]] = icmp sgt i32 [[N]], 0
+; CHECK-NEXT:    br i1 [[CMP9]], label %[[FOR_BODY_PREHEADER:.*]], label %[[FOR_COND_CLEANUP:.*]]
+; CHECK:       [[FOR_BODY_PREHEADER]]:
+; CHECK-NEXT:    [[WIDE_TRIP_COUNT:%.*]] = zext nneg i32 [[N]] to i64
+; CHECK-NEXT:    br label %[[FOR_BODY:.*]]
+; CHECK:       [[FOR_COND_CLEANUP_LOOPEXIT:.*]]:
+; CHECK-NEXT:    br label %[[FOR_COND_CLEANUP]]
+; CHECK:       [[FOR_COND_CLEANUP]]:
+; CHECK-NEXT:    ret void
+; CHECK:       [[FOR_BODY]]:
+; CHECK-NEXT:    [[INDVARS_IV:%.*]] = phi i64 [ 0, %[[FOR_BODY_PREHEADER]] ], [ [[INDVARS_IV_NEXT:%.*]], %[[WHILE_END:.*]] ]
+; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds ptr, ptr [[STRS]], i64 [[INDVARS_IV]]
+; CHECK-NEXT:    [[TMP0:%.*]] = load ptr, ptr [[ARRAYIDX]], align 8
+; CHECK-NEXT:    [[TMP1:%.*]] = load i8, ptr [[TMP0]], align 1
+; CHECK-NEXT:    [[TOBOOL_NOT6:%.*]] = icmp eq i8 [[TMP1]], 0
+; CHECK-NEXT:    br i1 [[TOBOOL_NOT6]], label %[[WHILE_END]], label %[[WHILE_BODY_PREHEADER:.*]]
+; CHECK:       [[WHILE_BODY_PREHEADER]]:
+; CHECK-NEXT:    [[SCEVGEP:%.*]] = getelementptr i8, ptr [[TMP0]], i64 1
+; CHECK-NEXT:    [[STRLEN:%.*]] = call i64 @strlen(ptr [[SCEVGEP]])
+; CHECK-NEXT:    [[TMP2:%.*]] = trunc i64 [[STRLEN]] to i32
+; CHECK-NEXT:    [[TMP3:%.*]] = add i32 [[TMP2]], 1
+; CHECK-NEXT:    br label %[[WHILE_BODY:.*]]
+; CHECK:       [[WHILE_BODY]]:
+; CHECK-NEXT:    [[COUNT_08:%.*]] = phi i32 [ [[INC:%.*]], %[[WHILE_BODY]] ], [ 0, %[[WHILE_BODY_PREHEADER]] ]
+; CHECK-NEXT:    [[S_07:%.*]] = phi ptr [ [[INCDEC_PTR:%.*]], %[[WHILE_BODY]] ], [ [[TMP0]], %[[WHILE_BODY_PREHEADER]] ]
+; CHECK-NEXT:    [[INCDEC_PTR]] = getelementptr inbounds nuw i8, ptr [[S_07]], i64 1
+; CHECK-NEXT:    [[INC]] = add nuw nsw i32 [[COUNT_08]], 1
+; CHECK-NEXT:    [[TMP4:%.*]] = load i8, ptr [[INCDEC_PTR]], align 1
+; CHECK-NEXT:    [[TOBOOL_NOT:%.*]] = icmp eq i8 [[TMP4]], 0
+; CHECK-NEXT:    br i1 [[TOBOOL_NOT]], label %[[WHILE_END_LOOPEXIT:.*]], label %[[WHILE_BODY]]
+; CHECK:       [[WHILE_END_LOOPEXIT]]:
+; CHECK-NEXT:    br label %[[WHILE_END]]
+; CHECK:       [[WHILE_END]]:
+; CHECK-NEXT:    [[COUNT_0_LCSSA:%.*]] = phi i32 [ 0, %[[FOR_BODY]] ], [ [[TMP3]], %[[WHILE_END_LOOPEXIT]] ]
+; CHECK-NEXT:    tail call void @usei(i32 [[COUNT_0_LCSSA]])
+; CHECK-NEXT:    [[INDVARS_IV_NEXT]] = add nuw nsw i64 [[INDVARS_IV]], 1
+; CHECK-NEXT:    [[EXITCOND_NOT:%.*]] = icmp eq i64 [[INDVARS_IV_NEXT]], [[WIDE_TRIP_COUNT]]
+; CHECK-NEXT:    br i1 [[EXITCOND_NOT]], label %[[FOR_COND_CLEANUP_LOOPEXIT]], label %[[FOR_BODY]]
+;
+entry:
+  %cmp9 = icmp sgt i32 %n, 0
+  br i1 %cmp9, label %for.body.preheader, label %for.cond.cleanup
+
+for.body.preheader:
+  %wide.trip.count = zext nneg i32 %n to i64
+  br label %for.body
+
+for.cond.cleanup:
+  ret void
+
+for.body:
+  %indvars.iv = phi i64 [ 0, %for.body.preheader ], [ %indvars.iv.next, %while.end ]
+  %arrayidx = getelementptr inbounds ptr, ptr %strs, i64 %indvars.iv
+  %0 = load ptr, ptr %arrayidx, align 8
+  %1 = load i8, ptr %0, align 1
+  %tobool.not6 = icmp eq i8 %1, 0
+  br i1 %tobool.not6, label %while.end, label %while.body
+
+while.body:
+  %count.08 = phi i32 [ %inc, %while.body ], [ 0, %for.body ]
+  %s.07 = phi ptr [ %incdec.ptr, %while.body ], [ %0, %for.body ]
+  %incdec.ptr = getelementptr inbounds nuw i8, ptr %s.07, i64 1
+  %inc = add nuw nsw i32 %count.08, 1
+  %2 = load i8, ptr %incdec.ptr, align 1
+  %tobool.not = icmp eq i8 %2, 0
+  br i1 %tobool.not, label %while.end, label %while.body
+
+while.end:
+  %count.0.lcssa = phi i32 [ 0, %for.body ], [ %inc, %while.body ]
+  tail call void @usei(i32 %count.0.lcssa) #2
+  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+  %exitcond.not = icmp eq i64 %indvars.iv.next, %wide.trip.count
+  br i1 %exitcond.not, label %for.cond.cleanup, label %for.body
+}
+
+define i64 @invalid_strlen_has_side_effects(ptr %str) {
+; CHECK-LABEL: define i64 @invalid_strlen_has_side_effects(
+; CHECK-SAME: ptr [[STR:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*]]:
+; CHECK-NEXT:    br label %[[WHILE_COND:.*]]
+; CHECK:       [[WHILE_COND]]:
+; CHECK-NEXT:    [[STR_ADDR_0:%.*]] = phi ptr [ [[STR]], %[[ENTRY]] ], [ [[INCDEC_PTR:%.*]], %[[WHILE_COND]] ]
+; CHECK-NEXT:    [[TMP0:%.*]] = load volatile i8, ptr [[STR_ADDR_0]], align 1
+; CHECK-NEXT:    [[CMP_NOT:%.*]] = icmp eq i8 [[TMP0]], 0
+; CHECK-NEXT:    [[INCDEC_PTR]] = getelementptr i8, ptr [[STR_ADDR_0]], i64 1
+; CHECK-NEXT:    br i1 [[CMP_NOT]], label %[[WHILE_END:.*]], label %[[WHILE_COND]]
+; CHECK:       [[WHILE_END]]:
+; CHECK-NEXT:    [[STR_ADDR_0_LCSSA:%.*]] = phi ptr [ [[STR_ADDR_0]], %[[WHILE_COND]] ]
+; CHECK-NEXT:    [[SUB_PTR_LHS_CAST:%.*]] = ptrtoint ptr [[STR_ADDR_0_LCSSA]] to i64
+; CHECK-NEXT:    [[SUB_PTR_RHS_CAST:%.*]] = ptrtoint ptr [[STR]] to i64
+; CHECK-NEXT:    [[SUB_PTR_SUB:%.*]] = sub i64 [[SUB_PTR_LHS_CAST]], [[SUB_PTR_RHS_CAST]]
+; CHECK-NEXT:    ret i64 [[SUB_PTR_SUB]]
+;
+entry:
+  br label %while.cond
+
+while.cond:
+  %str.addr.0 = phi ptr [ %str, %entry ], [ %incdec.ptr, %while.cond ]
+  %0 = load volatile i8, ptr %str.addr.0, align 1
+  %cmp.not = icmp eq i8 %0, 0
+  %incdec.ptr = getelementptr i8, ptr %str.addr.0, i64 1
+  br i1 %cmp.not, label %while.end, label %while.cond
+
+while.end:
+  %sub.ptr.lhs.cast = ptrtoint ptr %str.addr.0 to i64
+  %sub.ptr.rhs.cast = ptrtoint ptr %str to i64
+  %sub.ptr.sub = sub i64 %sub.ptr.lhs.cast, %sub.ptr.rhs.cast
+  ret i64 %sub.ptr.sub
+}
+
+
+define i8 @invalid_exit_phi_scev(ptr %str) {
+; CHECK-LABEL: define i8 @invalid_exit_phi_scev(
+; CHECK-SAME: ptr [[STR:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*]]:
+; CHECK-NEXT:    br label %[[WHILE_COND:.*]]
+; CHECK:       [[WHILE_COND]]:
+; CHECK-NEXT:    [[STR_ADDR_0:%.*]] = phi ptr [ [[STR]], %[[ENTRY]] ], [ [[INCDEC_PTR:%.*]], %[[WHILE_COND]] ]
+; CHECK-NEXT:    [[TMP0:%.*]] = load i8, ptr [[STR_ADDR_0]], align 1
+; CHECK-NEXT:    [[CMP_NOT:%.*]] = icmp eq i8 [[TMP0]], 0
+; CHECK-NEXT:    [[INCDEC_PTR]] = getelementptr i8, ptr [[STR_ADDR_0]], i64 1
+; CHECK-NEXT:    br i1 [[CMP_NOT]], label %[[WHILE_END:.*]], label %[[WHILE_COND]]
+; CHECK:       [[WHILE_END]]:
+; CHECK-NEXT:    [[STR_ADDR_0_LCSSA:%.*]] = phi ptr [ [[STR_ADDR_0]], %[[WHILE_COND]] ]
+; CHECK-NEXT:    [[DOTLCSSA:%.*]] = phi i8 [ [[TMP0]], %[[WHILE_COND]] ]
+; CHECK-NEXT:    [[SUB_PTR_LHS_CAST:%.*]] = ptrtoint ptr [[STR_ADDR_0_LCSSA]] to i64
+; CHECK-NEXT:    [[SUB_PTR_RHS_CAST:%.*]] = ptrtoint ptr [[STR]] to i64
+; CHECK-NEXT:    [[SUB_PTR_SUB:%.*]] = sub i64 [[SUB_PTR_LHS_CAST]], [[SUB_PTR_RHS_CAST]]
+; CHECK-NEXT:    ret i8 [[DOTLCSSA]]
+;
+entry:
+  br label %while.cond
+
+while.cond:
+  %str.addr.0 = phi ptr [ %str, %entry ], [ %incdec.ptr, %while.cond ]
+  %0 = load i8, ptr %str.addr.0, align 1
+  %cmp.not = icmp eq i8 %0, 0
+  %incdec.ptr = getelementptr i8, ptr %str.addr.0, i64 1
+  br i1 %cmp.not, label %while.end, label %while.cond
+
+while.end:
+  %sub.ptr.lhs.cast = ptrtoint ptr %str.addr.0 to i64
+  %sub.ptr.rhs.cast = ptrtoint ptr %str to i64
+  %sub.ptr.sub = sub i64 %sub.ptr.lhs.cast, %sub.ptr.rhs.cast
+
+  ; %0.lcssa has invalid scev rec {%0} expected to be {%str,+,constant}
+  ret i8 %0
+}
+
+
+
+define i64 @invalid_branch_cond(ptr %str) {
+; CHECK-LABEL: define i64 @invalid_branch_cond(
+; CHECK-SAME: ptr [[STR:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*]]:
+; CHECK-NEXT:    br label %[[WHILE_COND:.*]]
+; CHECK:       [[WHILE_COND]]:
+; CHECK-NEXT:    [[STR_ADDR_0:%.*]] = phi ptr [ [[STR]], %[[ENTRY]] ], [ [[INCDEC_PTR:%.*]], %[[WHILE_COND]] ]
+; CHECK-NEXT:    [[TMP0:%.*]] = load i8, ptr [[STR_ADDR_0]], align 1
+; CHECK-NEXT:    [[CMP_NOT:%.*]] = icmp eq i8 [[TMP0]], 10
+; CHECK-NEXT:    [[INCDEC_PTR]] = getelementptr i8, ptr [[STR_ADDR_0]], i64 1
+; CHECK-NEXT:    br i1 [[CMP_NOT]], label %[[WHILE_END:.*]], label %[[WHILE_COND]]
+; CHECK:       [[WHILE_END]]:
+; CHECK-NEXT:    [[STR_ADDR_0_LCSSA:%.*]] = phi ptr [ [[STR_ADDR_0]], %[[WHILE_COND]] ]
+; CHECK-NEXT:    [[SUB_PTR_LHS_CAST:%.*]] = ptrtoint ptr [[STR_ADDR_0_LCSSA]] to i64
+; CHECK-NEXT:    [[SUB_PTR_RHS_CAST:%.*]] = ptrtoint ptr [[STR]] to i64
+; CHECK-NEXT:    [[SUB_PTR_SUB:%.*]] = sub i64 [[SUB_PTR_LHS_CAST]], [[SUB_PTR_RHS_CAST]]
+; CHECK-NEXT:    ret i64 [[SUB_PTR_SUB]]
+;
+entry:
+  br label %while.cond
+
+while.cond:
+  %str.addr.0 = phi ptr [ %str, %entry ], [ %incdec.ptr, %while.cond ]
+  %0 = load i8, ptr %str.addr.0, align 1
+
+  ; We compare against '\n' instead of '\0'
+  %cmp.not = icmp eq i8 %0, 10
+
+  %incdec.ptr = getelementptr i8, ptr %str.addr.0, i64 1
+  br i1 %cmp.not, label %while.end, label %while.cond
+
+while.end:
+  %sub.ptr.lhs.cast = ptrtoint ptr %str.addr.0 to i64
+  %sub.ptr.rhs.cast = ptrtoint ptr %str to i64
+  %sub.ptr.sub = sub i64 %sub.ptr.lhs.cast, %sub.ptr.rhs.cast
+  ret i64 %sub.ptr.sub
+}
+
+define i64 @invalid_unknown_step_size(ptr %str, i64 %step) {
+; CHECK-LABEL: define i64 @invalid_unknown_step_size(
+; CHECK-SAME: ptr [[STR:%.*]], i64 [[STEP:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*]]:
+; CHECK-NEXT:    br label %[[WHILE_COND:.*]]
+; CHECK:       [[WHILE_COND]]:
+; CHECK-NEXT:    [[STR_ADDR_0:%.*]] = phi ptr [ [[STR]], %[[ENTRY]] ], [ [[INCDEC_PTR:%.*]], %[[WHILE_COND]] ]
+; CHECK-NEXT:    [[TMP0:%.*]] = load i8, ptr [[STR_ADDR_0]], align 1
+; CHECK-NEXT:    [[CMP_NOT:%.*]] = icmp eq i8 [[TMP0]], 0
+; CHECK-NEXT:    [[INCDEC_PTR]] = getelementptr i8, ptr [[STR_ADDR_0]], i64 [[STEP]]
+; CHECK-NEXT:    br i1 [[CMP_NOT]], label %[[WHILE_END:.*]], label %[[WHILE_COND]]
+; CHECK:       [[WHILE_END]]:
+; CHECK-NEXT:    [[STR_ADDR_0_LCSSA:%.*]] = phi ptr [ [[STR_ADDR_0]], %[[WHILE_COND]] ]
+; CHECK-NEXT:    [[SUB_PTR_LHS_CAST:%.*]] = ptrtoint ptr [[STR_ADDR_0_LCSSA]] to i64
+; CHECK-NEXT:    [[SUB_PTR_RHS_CAST:%.*]] = ptrtoint ptr [[STR]] to i64
+; CHECK-NEXT:    [[SUB_PTR_SUB:%.*]] = sub i64 [[SUB_PTR_LHS_CAST]], [[SUB_PTR_RHS_CAST]]
+; CHECK-NEXT:    ret i64 [[SUB_PTR_SUB]]
+;
+entry:
+  br label %while.cond
+
+while.cond:
+  %str.addr.0 = phi ptr [ %str, %entry ], [ %incdec.ptr, %while.cond ]
+  %0 = load i8, ptr %str.addr.0, align 1
+  %cmp.not = icmp eq i8 %0, 0
+  %incdec.ptr = getelementptr i8, ptr %str.addr.0, i64 %step
+  br i1 %cmp.not, label %while.end, label %while.cond
+
+while.end:
+  %sub.ptr.lhs.cast = ptrtoint ptr %str.addr.0 to i64
+  %sub.ptr.rhs.cast = ptrtoint ptr %str to i64
+  %sub.ptr.sub = sub i64 %sub.ptr.lhs.cast, %sub.ptr.rhs.cast
+  ret i64 %sub.ptr.sub
+}
+
+declare ptr @pure(ptr) #0;
+attributes #0 = { mustprogress nofree norecurse nosync nounwind willreturn memory(none) }
+
+define i64 @invalid_add_rec(ptr %str) {
+; CHECK-LABEL: define i64 @invalid_add_rec(
+; CHECK-SAME: ptr [[STR:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*]]:
+; CHECK-NEXT:    br label %[[WHILE_COND:.*]]
+; CHECK:       [[WHILE_COND]]:
+; CHECK-NEXT:    [[STR_ADDR_0:%.*]] = phi ptr [ [[STR]], %[[ENTRY]] ], [ [[INCDEC_PTR:%.*]], %[[WHILE_COND]] ]
+; CHECK-NEXT:    [[INDIRECT:%.*]] = tail call ptr @pure(ptr [[STR_ADDR_0]])
+; CHECK-NEXT:    [[TMP0:%.*]] = load i8, ptr [[INDIRECT]], align 1
+; CHECK-NEXT:    [[CMP_NOT:%.*]] = icmp eq i8 [[TMP0]], 0
+; CHECK-NEXT:    [[INCDEC_PTR]] = getelementptr i8, ptr [[STR_ADDR_0]], i64 1
+; CHECK-NEXT:    br i1 [[CMP_NOT]], label %[[WHILE_END:.*]], label %[[WHILE_COND]]
+; CHECK:       [[WHILE_END]]:
+; CHECK-NEXT:    [[STR_ADDR_0_LCSSA:%.*]] = phi ptr [ [[STR_ADDR_0]], %[[WHILE_COND]] ]
+; CHECK-NEXT:    [[SUB_PTR_LHS_CAST:%.*]] = ptrtoint ptr [[STR_ADDR_0_LCSSA]] to i64
+; CHECK-NEXT:    [[SUB_PTR_RHS_CAST:%.*]] = ptrtoint ptr [[STR]] to i64
+; CHECK-NEXT:    [[SUB_PTR_SUB:%.*]] = sub i64 [[SUB_PTR_LHS_CAST]], [[SUB_PTR_RHS_CAST]]
+; CHECK-NEXT:    ret i64 [[SUB_PTR_SUB]]
+;
+entry:
+  br label %while.cond
+
+while.cond:
+  %str.addr.0 = phi ptr [ %str, %entry ], [ %incdec.ptr, %while.cond ]
+  %indirect = tail call ptr @pure(ptr %str.addr.0)
+  %0 = load i8, ptr %indirect, align 1
+  %cmp.not = icmp eq i8 %0, 0
+  %incdec.ptr = getelementptr i8, ptr %str.addr.0, i64 1
+  br i1 %cmp.not, label %while.end, label %while.cond
+
+while.end:
+  %sub.ptr.lhs.cast = ptrtoint ptr %str.addr.0 to i64
+  %sub.ptr.rhs.cast = ptrtoint ptr %str to i64
+  %sub.ptr.sub = sub i64 %sub.ptr.lhs.cast, %sub.ptr.rhs.cast
+  ret i64 %sub.ptr.sub
+}
+
diff --git a/llvm/test/Transforms/LoopIdiom/wcslen16.ll b/llvm/test/Transforms/LoopIdiom/wcslen16.ll
new file mode 100644
index 0000000000000..d3b0b8d208cd8
--- /dev/null
+++ b/llvm/test/Transforms/LoopIdiom/wcslen16.ll
@@ -0,0 +1,126 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -passes='loop(loop-idiom),verify' < %s -S | FileCheck %s
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define i64 @valid_strlen16(ptr %src) {
+; CHECK-LABEL: define i64 @valid_strlen16(
+; CHECK-SAME: ptr [[SRC:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*]]:
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq ptr [[SRC]], null
+; CHECK-NEXT:    br i1 [[CMP]], label %[[RETURN:.*]], label %[[LOR_LHS_FALSE:.*]]
+; CHECK:       [[LOR_LHS_FALSE]]:
+; CHECK-NEXT:    [[TMP0:%.*]] = load i16, ptr [[SRC]], align 2
+; CHECK-NEXT:    [[CMP1:%.*]] = icmp eq i16 [[TMP0]], 0
+; CHECK-NEXT:    br i1 [[CMP1]], label %[[RETURN]], label %[[WHILE_COND_PREHEADER:.*]]
+; CHECK:       [[WHILE_COND_PREHEADER]]:
+; CHECK-NEXT:    [[NEWGEP:%.*]] = getelementptr i8, ptr [[SRC]], i64 2
+; CHECK-NEXT:    [[WCSLEN:%.*]] = call i64 @wcslen(ptr [[NEWGEP]])
+; CHECK-NEXT:    [[TMP1:%.*]] = shl i64 [[WCSLEN]], 1
+; CHECK-NEXT:    [[TMP2:%.*]] = add i64 [[TMP1]], 2
+; CHECK-NEXT:    [[END:%.*]] = getelementptr i8, ptr [[SRC]], i64 [[TMP2]]
+; CHECK-NEXT:    br label %[[WHILE_COND:.*]]
+; CHECK:       [[WHILE_COND]]:
+; CHECK-NEXT:    [[SRC_PN:%.*]] = phi ptr [ [[CURR_0:%.*]], %[[WHILE_COND]] ], [ [[SRC]], %[[WHILE_COND_PREHEADER]] ]
+; CHECK-NEXT:    [[CURR_0]] = getelementptr inbounds i8, ptr [[SRC_PN]], i64 2
+; CHECK-NEXT:    [[TMP3:%.*]] = load i16, ptr [[CURR_0]], align 2
+; CHECK-NEXT:    [[TOBOOL_NOT:%.*]] = icmp eq i16 [[TMP3]], 0
+; CHECK-NEXT:    br i1 [[TOBOOL_NOT]], label %[[WHILE_END:.*]], label %[[WHILE_COND]]
+; CHECK:       [[WHILE_END]]:
+; CHECK-NEXT:    [[SUB_PTR_LHS_CAST:%.*]] = ptrtoint ptr [[END]] to i64
+; CHECK-NEXT:    [[SUB_PTR_RHS_CAST:%.*]] = ptrtoint ptr [[SRC]] to i64
+; CHECK-NEXT:    [[SUB_PTR_SUB:%.*]] = sub i64 [[SUB_PTR_LHS_CAST]], [[SUB_PTR_RHS_CAST]]
+; CHECK-NEXT:    [[SUB_PTR_DIV:%.*]] = ashr exact i64 [[SUB_PTR_SUB]], 1
+; CHECK-NEXT:    br label %[[RETURN]]
+; CHECK:       [[RETURN]]:
+; CHECK-NEXT:    [[RETVAL_0:%.*]] = phi i64 [ [[SUB_PTR_DIV]], %[[WHILE_END]] ], [ 0, %[[LOR_LHS_FALSE]] ], [ 0, %[[ENTRY]] ]
+; CHECK-NEXT:    ret i64 [[RETVAL_0]]
+;
+entry:
+  %cmp = icmp eq ptr %src, null
+  br i1 %cmp, label %return, label %lor.lhs.false
+
+lor.lhs.false:                                    ; preds = %entry
+  %0 = load i16, ptr %src, align 2
+  %cmp1 = icmp eq i16 %0, 0
+  br i1 %cmp1, label %return, label %while.cond
+
+while.cond:                                       ; preds = %lor.lhs.false, %while.cond
+  %src.pn = phi ptr [ %curr.0, %while.cond ], [ %src, %lor.lhs.false ]
+  %curr.0 = getelementptr inbounds i8, ptr %src.pn, i64 2
+  %1 = load i16, ptr %curr.0, align 2
+  %tobool.not = icmp eq i16 %1, 0
+  br i1 %tobool.not, label %while.end, label %while.cond
+
+while.end:                                        ; preds = %while.cond
+  %sub.ptr.lhs.cast = ptrtoint ptr %curr.0 to i64
+  %sub.ptr.rhs.cast = ptrtoint ptr %src to i64
+  %sub.ptr.sub = sub i64 %sub.ptr.lhs.cast, %sub.ptr.rhs.cast
+  %sub.ptr.div = ashr exact i64 %sub.ptr.sub, 1
+  br label %return
+
+return:                                           ; preds = %entry, %lor.lhs.false, %while.end
+  %retval.0 = phi i64 [ %sub.ptr.div, %while.end ], [ 0, %lor.lhs.false ], [ 0, %entry ]
+  ret i64 %retval.0
+}
+
+define i64 @invalid_char_size(ptr %src) {
+; CHECK-LABEL: define i64 @invalid_char_size(
+; CHECK-SAME: ptr [[SRC:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*]]:
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq ptr [[SRC]], null
+; CHECK-NEXT:    br i1 [[CMP]], label %[[RETURN:.*]], label %[[LOR_LHS_FALSE:.*]]
+; CHECK:       [[LOR_LHS_FALSE]]:
+; CHECK-NEXT:    [[TMP0:%.*]] = load i32, ptr [[SRC]], align 2
+; CHECK-NEXT:    [[CMP1:%.*]] = icmp eq i32 [[TMP0]], 0
+; CHECK-NEXT:    br i1 [[CMP1]], label %[[RETURN]], label %[[WHILE_COND_PREHEADER:.*]]
+; CHECK:       [[WHILE_COND_PREHEADER]]:
+; CHECK-NEXT:    br label %[[WHILE_COND:.*]]
+; CHECK:       [[WHILE_COND]]:
+; CHECK-NEXT:    [[SRC_PN:%.*]] = phi ptr [ [[CURR_0:%.*]], %[[WHILE_COND]] ], [ [[SRC]], %[[WHILE_COND_PREHEADER]] ]
+; CHECK-NEXT:    [[CURR_0]] = getelementptr inbounds i8, ptr [[SRC_PN]], i64 4
+; CHECK-NEXT:    [[TMP1:%.*]] = load i32, ptr [[CURR_0]], align 4
+; CHECK-NEXT:    [[TOBOOL_NOT:%.*]] = icmp eq i32 [[TMP1]], 0
+; CHECK-NEXT:    br i1 [[TOBOOL_NOT]], label %[[WHILE_END:.*]], label %[[WHILE_COND]]
+; CHECK:       [[WHILE_END]]:
+; CHECK-NEXT:    [[CURR_0_LCSSA:%.*]] = phi ptr [ [[CURR_0]], %[[WHILE_COND]] ]
+; CHECK-NEXT:    [[SUB_PTR_LHS_CAST:%.*]] = ptrtoint ptr [[CURR_0_LCSSA]] to i64
+; CHECK-NEXT:    [[SUB_PTR_RHS_CAST:%.*]] = ptrtoint ptr [[SRC]] to i64
+; CHECK-NEXT:    [[SUB_PTR_SUB:%.*]] = sub i64 [[SUB_PTR_LHS_CAST]], [[SUB_PTR_RHS_CAST]]
+; CHECK-NEXT:    [[SUB_PTR_DIV:%.*]] = ashr exact i64 [[SUB_PTR_SUB]], 2
+; CHECK-NEXT:    br label %[[RETURN]]
+; CHECK:       [[RETURN]]:
+; CHECK-NEXT:    [[RETVAL_0:%.*]] = phi i64 [ [[SUB_PTR_DIV]], %[[WHILE_END]] ], [ 0, %[[LOR_LHS_FALSE]] ], [ 0, %[[ENTRY]] ]
+; CHECK-NEXT:    ret i64 [[RETVAL_0]]
+;
+entry:
+  %cmp = icmp eq ptr %src, null
+  br i1 %cmp, label %return, label %lor.lhs.false
+
+lor.lhs.false:                                    ; preds = %entry
+  %0 = load i32, ptr %src, align 2
+  %cmp1 = icmp eq i32 %0, 0
+  br i1 %cmp1, label %return, label %while.cond
+
+while.cond:                                       ; preds = %lor.lhs.false, %while.cond
+  %src.pn = phi ptr [ %curr.0, %while.cond ], [ %src, %lor.lhs.false ]
+  %curr.0 = getelementptr inbounds i8, ptr %src.pn, i64 4
+  %1 = load i32, ptr %curr.0, align 4
+  %tobool.not = icmp eq i32 %1, 0
+  br i1 %tobool.not, label %while.end, label %while.cond
+
+while.end:                                        ; preds = %while.cond
+  %sub.ptr.lhs.cast = ptrtoint ptr %curr.0 to i64
+  %sub.ptr.rhs.cast = ptrtoint ptr %src to i64
+  %sub.ptr.sub = sub i64 %sub.ptr.lhs.cast, %sub.ptr.rhs.cast
+  %sub.ptr.div = ashr exact i64 %sub.ptr.sub, 2
+  br label %return
+
+return:                                           ; preds = %entry, %lor.lhs.false, %while.end
+  %retval.0 = phi i64 [ %sub.ptr.div, %while.end ], [ 0, %lor.lhs.false ], [ 0, %entry ]
+  ret i64 %retval.0
+}
+!llvm.module.flags = !{!0}
+!0 = !{i32 1, !"wchar_size", i32 2}
+
diff --git a/llvm/test/Transforms/LoopIdiom/wcslen32.ll b/llvm/test/Transforms/LoopIdiom/wcslen32.ll
new file mode 100644
index 0000000000000..488afff86c245
--- /dev/null
+++ b/llvm/test/Transforms/LoopIdiom/wcslen32.ll
@@ -0,0 +1,134 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -passes='loop(loop-idiom),verify' < %s -S | FileCheck %s
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define i64 @valid_wcslen32(ptr %src) {
+; CHECK-LABEL: define i64 @valid_wcslen32(
+; CHECK-SAME: ptr [[SRC:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*]]:
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq ptr [[SRC]], null
+; CHECK-NEXT:    br i1 [[CMP]], label %[[RETURN:.*]], label %[[LOR_LHS_FALSE:.*]]
+; CHECK:       [[LOR_LHS_FALSE]]:
+; CHECK-NEXT:    [[TMP0:%.*]] = load i32, ptr [[SRC]], align 4
+; CHECK-NEXT:    [[CMP1:%.*]] = icmp eq i32 [[TMP0]], 0
+; CHECK-NEXT:    br i1 [[CMP1]], label %[[RETURN]], label %[[WHILE_COND_PREHEADER:.*]]
+; CHECK:       [[WHILE_COND_PREHEADER]]:
+; CHECK-NEXT:    [[NEWGEP:%.*]] = getelementptr i8, ptr [[SRC]], i64 4
+; CHECK-NEXT:    [[WCSLEN:%.*]] = call i64 @wcslen(ptr [[NEWGEP]])
+; CHECK-NEXT:    [[TMP1:%.*]] = shl i64 [[WCSLEN]], 2
+; CHECK-NEXT:    [[TMP2:%.*]] = add i64 [[TMP1]], 4
+; CHECK-NEXT:    [[END:%.*]] = getelementptr i8, ptr [[SRC]], i64 [[TMP2]]
+; CHECK-NEXT:    br label %[[WHILE_COND:.*]]
+; CHECK:       [[WHILE_COND]]:
+; CHECK-NEXT:    [[SRC_PN:%.*]] = phi ptr [ [[CURR_0:%.*]], %[[WHILE_COND]] ], [ [[SRC]], %[[WHILE_COND_PREHEADER]] ]
+; CHECK-NEXT:    [[CURR_0]] = getelementptr inbounds i8, ptr [[SRC_PN]], i64 4
+; CHECK-NEXT:    [[TMP3:%.*]] = load i32, ptr [[CURR_0]], align 4
+; CHECK-NEXT:    [[TOBOOL_NOT:%.*]] = icmp eq i32 [[TMP3]], 0
+; CHECK-NEXT:    br i1 [[TOBOOL_NOT]], label %[[WHILE_END:.*]], label %[[WHILE_COND]]
+; CHECK:       [[WHILE_END]]:
+; CHECK-NEXT:    [[SUB_PTR_LHS_CAST:%.*]] = ptrtoint ptr [[END]] to i64
+; CHECK-NEXT:    [[SUB_PTR_RHS_CAST:%.*]] = ptrtoint ptr [[SRC]] to i64
+; CHECK-NEXT:    [[SUB_PTR_SUB:%.*]] = sub i64 [[SUB_PTR_LHS_CAST]], [[SUB_PTR_RHS_CAST]]
+; CHECK-NEXT:    [[SUB_PTR_DIV:%.*]] = ashr exact i64 [[SUB_PTR_SUB]], 2
+; CHECK-NEXT:    br label %[[RETURN]]
+; CHECK:       [[RETURN]]:
+; CHECK-NEXT:    [[RETVAL_0:%.*]] = phi i64 [ [[SUB_PTR_DIV]], %[[WHILE_END]] ], [ 0, %[[LOR_LHS_FALSE]] ], [ 0, %[[ENTRY]] ]
+; CHECK-NEXT:    ret i64 [[RETVAL_0]]
+;
+entry:
+  %cmp = icmp eq ptr %src, null
+  br i1 %cmp, label %return, label %lor.lhs.false
+
+lor.lhs.false:                                    ; preds = %entry
+  %0 = load i32, ptr %src, align 4
+  %cmp1 = icmp eq i32 %0, 0
+  br i1 %cmp1, label %return, label %while.cond.preheader
+
+while.cond.preheader:                             ; preds = %lor.lhs.false
+  br label %while.cond
+
+while.cond:                                       ; preds = %while.cond.preheader, %while.cond
+  %src.pn = phi ptr [ %curr.0, %while.cond ], [ %src, %while.cond.preheader ]
+  %curr.0 = getelementptr inbounds i8, ptr %src.pn, i64 4
+  %1 = load i32, ptr %curr.0, align 4
+  %tobool.not = icmp eq i32 %1, 0
+  br i1 %tobool.not, label %while.end, label %while.cond
+
+while.end:                                        ; preds = %while.cond
+  %curr.0.lcssa = phi ptr [ %curr.0, %while.cond ]
+  %sub.ptr.lhs.cast = ptrtoint ptr %curr.0.lcssa to i64
+  %sub.ptr.rhs.cast = ptrtoint ptr %src to i64
+  %sub.ptr.sub = sub i64 %sub.ptr.lhs.cast, %sub.ptr.rhs.cast
+  %sub.ptr.div = ashr exact i64 %sub.ptr.sub, 2
+  br label %return
+
+return:                                           ; preds = %entry, %lor.lhs.false, %while.end
+  %retval.0 = phi i64 [ %sub.ptr.div, %while.end ], [ 0, %lor.lhs.false ], [ 0, %entry ]
+  ret i64 %retval.0
+}
+
+define i64 @invalid_char_size(ptr %src) {
+; CHECK-LABEL: define i64 @invalid_char_size(
+; CHECK-SAME: ptr [[SRC:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*]]:
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq ptr [[SRC]], null
+; CHECK-NEXT:    br i1 [[CMP]], label %[[RETURN:.*]], label %[[LOR_LHS_FALSE:.*]]
+; CHECK:       [[LOR_LHS_FALSE]]:
+; CHECK-NEXT:    [[TMP0:%.*]] = load i16, ptr [[SRC]], align 2
+; CHECK-NEXT:    [[CMP1:%.*]] = icmp eq i16 [[TMP0]], 0
+; CHECK-NEXT:    br i1 [[CMP1]], label %[[RETURN]], label %[[WHILE_COND_PREHEADER:.*]]
+; CHECK:       [[WHILE_COND_PREHEADER]]:
+; CHECK-NEXT:    br label %[[WHILE_COND:.*]]
+; CHECK:       [[WHILE_COND]]:
+; CHECK-NEXT:    [[SRC_PN:%.*]] = phi ptr [ [[CURR_0:%.*]], %[[WHILE_COND]] ], [ [[SRC]], %[[WHILE_COND_PREHEADER]] ]
+; CHECK-NEXT:    [[CURR_0]] = getelementptr inbounds i8, ptr [[SRC_PN]], i64 2
+; CHECK-NEXT:    [[TMP1:%.*]] = load i16, ptr [[CURR_0]], align 2
+; CHECK-NEXT:    [[TOBOOL_NOT:%.*]] = icmp eq i16 [[TMP1]], 0
+; CHECK-NEXT:    br i1 [[TOBOOL_NOT]], label %[[WHILE_END:.*]], label %[[WHILE_COND]]
+; CHECK:       [[WHILE_END]]:
+; CHECK-NEXT:    [[CURR_0_LCSSA:%.*]] = phi ptr [ [[CURR_0]], %[[WHILE_COND]] ]
+; CHECK-NEXT:    [[SUB_PTR_LHS_CAST:%.*]] = ptrtoint ptr [[CURR_0_LCSSA]] to i64
+; CHECK-NEXT:    [[SUB_PTR_RHS_CAST:%.*]] = ptrtoint ptr [[SRC]] to i64
+; CHECK-NEXT:    [[SUB_PTR_SUB:%.*]] = sub i64 [[SUB_PTR_LHS_CAST]], [[SUB_PTR_RHS_CAST]]
+; CHECK-NEXT:    [[SUB_PTR_DIV:%.*]] = ashr exact i64 [[SUB_PTR_SUB]], 1
+; CHECK-NEXT:    br label %[[RETURN]]
+; CHECK:       [[RETURN]]:
+; CHECK-NEXT:    [[RETVAL_0:%.*]] = phi i64 [ [[SUB_PTR_DIV]], %[[WHILE_END]] ], [ 0, %[[LOR_LHS_FALSE]] ], [ 0, %[[ENTRY]] ]
+; CHECK-NEXT:    ret i64 [[RETVAL_0]]
+;
+entry:
+  %cmp = icmp eq ptr %src, null
+  br i1 %cmp, label %return, label %lor.lhs.false
+
+lor.lhs.false:                                    ; preds = %entry
+  %0 = load i16, ptr %src, align 2
+  %cmp1 = icmp eq i16 %0, 0
+  br i1 %cmp1, label %return, label %while.cond.preheader
+
+while.cond.preheader:                             ; preds = %lor.lhs.false
+  br label %while.cond
+
+while.cond:                                       ; preds = %while.cond.preheader, %while.cond
+  %src.pn = phi ptr [ %curr.0, %while.cond ], [ %src, %while.cond.preheader ]
+  %curr.0 = getelementptr inbounds i8, ptr %src.pn, i64 2
+  %1 = load i16, ptr %curr.0, align 2
+  %tobool.not = icmp eq i16 %1, 0
+  br i1 %tobool.not, label %while.end, label %while.cond
+
+while.end:                                        ; preds = %while.cond
+  %curr.0.lcssa = phi ptr [ %curr.0, %while.cond ]
+  %sub.ptr.lhs.cast = ptrtoint ptr %curr.0.lcssa to i64
+  %sub.ptr.rhs.cast = ptrtoint ptr %src to i64
+  %sub.ptr.sub = sub i64 %sub.ptr.lhs.cast, %sub.ptr.rhs.cast
+  %sub.ptr.div = ashr exact i64 %sub.ptr.sub, 1
+  br label %return
+
+return:                                           ; preds = %entry, %lor.lhs.false, %while.end
+  %retval.0 = phi i64 [ %sub.ptr.div, %while.end ], [ 0, %lor.lhs.false ], [ 0, %entry ]
+  ret i64 %retval.0
+}
+!llvm.module.flags = !{!0}
+!0 = !{i32 1, !"wchar_size", i32 4}
+