Index: llvm/include/llvm/IR/ConstantRange.h
===================================================================
--- llvm/include/llvm/IR/ConstantRange.h
+++ llvm/include/llvm/IR/ConstantRange.h
@@ -526,6 +526,11 @@
   /// \p IntMinIsPoison is false.
   ConstantRange abs(bool IntMinIsPoison = false) const;
 
+  /// Calculate absolute value range. If the original range contains zero, then
+  /// the resulting range will be bounded if and only if \p ZeroIsPoison is
+  /// false.
+  ConstantRange ctlz(bool ZeroIsPoison = false) const;
+
   /// Represents whether an operation on the given constant range is known to
   /// always or never overflow.
   enum class OverflowResult {
Index: llvm/lib/IR/ConstantRange.cpp
===================================================================
--- llvm/lib/IR/ConstantRange.cpp
+++ llvm/lib/IR/ConstantRange.cpp
@@ -945,6 +945,7 @@
   case Intrinsic::smin:
   case Intrinsic::smax:
   case Intrinsic::abs:
+  case Intrinsic::ctlz:
     return true;
   default:
     return false;
@@ -976,6 +977,12 @@
     assert(IntMinIsPoison->getBitWidth() == 1 && "Must be boolean");
     return Ops[0].abs(IntMinIsPoison->getBoolValue());
   }
+  case Intrinsic::ctlz: {
+    const APInt *ZeroIsPoison = Ops[1].getSingleElement();
+    assert(ZeroIsPoison && "Must be known (immarg)");
+    assert(ZeroIsPoison->getBitWidth() == 1 && "Must be boolean");
+    return Ops[0].ctlz(ZeroIsPoison->getBoolValue());
+  }
   default:
     assert(!isIntrinsicSupported(IntrinsicID) && "Shouldn't be supported");
     llvm_unreachable("Unsupported intrinsic");
@@ -1667,6 +1674,45 @@
                                     APIntOps::umax(-SMin, SMax) + 1);
 }
 
+ConstantRange ConstantRange::ctlz(bool ZeroIsPoison) const {
+  if (isEmptySet())
+    return getEmpty();
+
+  APInt Zero = APInt::getZero(getBitWidth());
+  if (ZeroIsPoison && contains(Zero)) {
+    // ZeroIsPoison is set, and zero is contained. We discern three cases, in
+    // which a zero can appear:
+    // 1) Lower is zero, handling cases of kind [0, 1), [0, 2), etc.
+    // 2) Upper is zero, wrapped set, handling cases of kind [3, 0], etc.
+    // 3) Zero contained in a wrapped set, e.g., [3, 2), [3, 1), etc.
+
+    if (getLower().isZero()) {
+      if ((getUpper() - 1).isZero()) {
+        // We have in input interval of kind [0, 1). In this case we cannot
+        // really help but return empty-set.
+        return getEmpty();
+      }
+
+      // Compute the resulting range by excluding zero from Lower.
+      return ConstantRange(
+          APInt(getBitWidth(), (getUpper() - 1).countLeadingZeros()),
+          APInt(getBitWidth(), (getLower() + 1).countLeadingZeros() + 1));
+    } else if ((getUpper() - 1).isZero()) {
+      // Compute the resulting range by excluding zero from Upper.
+      return ConstantRange(
+          Zero, APInt(getBitWidth(), getLower().countLeadingZeros() + 1));
+    } else {
+      return ConstantRange(Zero, APInt(getBitWidth(), getBitWidth()));
+    }
+  }
+
+  // Zero is either safe or not in the range. The output range is composed by
+  // the result of countLeadingZero of the two extremes.
+  return getNonEmpty(
+      APInt(getBitWidth(), getUnsignedMax().countLeadingZeros()),
+      APInt(getBitWidth(), getUnsignedMin().countLeadingZeros() + 1));
+}
+
 ConstantRange::OverflowResult ConstantRange::unsignedAddMayOverflow(
     const ConstantRange &Other) const {
   if (isEmptySet() || Other.isEmptySet())
Index: llvm/test/Transforms/CorrelatedValuePropagation/range.ll
===================================================================
--- llvm/test/Transforms/CorrelatedValuePropagation/range.ll
+++ llvm/test/Transforms/CorrelatedValuePropagation/range.ll
@@ -964,12 +964,10 @@
 ; CHECK-NEXT:    br i1 [[CMP]], label [[IF:%.*]], label [[ELSE:%.*]]
 ; CHECK:       if:
 ; CHECK-NEXT:    [[CTLZ:%.*]] = call i16 @llvm.ctlz.i16(i16 [[X]], i1 false)
-; CHECK-NEXT:    [[RES:%.*]] = icmp uge i16 [[CTLZ]], 8
-; CHECK-NEXT:    ret i1 [[RES]]
+; CHECK-NEXT:    ret i1 true
 ; CHECK:       else:
 ; CHECK-NEXT:    [[CTLZ2:%.*]] = call i16 @llvm.ctlz.i16(i16 [[X]], i1 false)
-; CHECK-NEXT:    [[RES2:%.*]] = icmp ult i16 [[CTLZ2]], 8
-; CHECK-NEXT:    ret i1 [[RES2]]
+; CHECK-NEXT:    ret i1 true
 ;
   %cmp = icmp ult i16 %x, 256
   br i1 %cmp, label %if, label %else
Index: llvm/unittests/IR/ConstantRangeTest.cpp
===================================================================
--- llvm/unittests/IR/ConstantRangeTest.cpp
+++ llvm/unittests/IR/ConstantRangeTest.cpp
@@ -2397,6 +2397,21 @@
       });
 }
 
+TEST_F(ConstantRangeTest, Ctlz) {
+  TestUnaryOpExhaustive([](const ConstantRange &CR) { return CR.ctlz(); },
+                        [](const APInt &N) {
+                          return APInt(N.getBitWidth(), N.countLeadingZeros());
+                        });
+
+  TestUnaryOpExhaustive(
+      [](const ConstantRange &CR) { return CR.ctlz(/*ZeroIsPoison=*/true); },
+      [](const APInt &N) -> std::optional<APInt> {
+        if (N.isZero())
+          return std::nullopt;
+        return APInt(N.getBitWidth(), N.countLeadingZeros());
+      });
+}
+
 TEST_F(ConstantRangeTest, castOps) {
   ConstantRange A(APInt(16, 66), APInt(16, 128));
   ConstantRange FpToI8 = A.castOp(Instruction::FPToSI, 8);