Index: llvm/lib/Analysis/InstructionSimplify.cpp
===================================================================
--- llvm/lib/Analysis/InstructionSimplify.cpp
+++ llvm/lib/Analysis/InstructionSimplify.cpp
@@ -2826,44 +2826,6 @@
   return nullptr;
 }
 
-static Value *simplifyICmpWithAbsNabs(CmpInst::Predicate Pred, Value *Op0,
-                                      Value *Op1) {
-  // We need a comparison with a constant.
-  const APInt *C;
-  if (!match(Op1, m_APInt(C)))
-    return nullptr;
-
-  // matchSelectPattern returns the negation part of an abs pattern in SP1.
-  // If the negate has an NSW flag, abs(INT_MIN) is undefined. Without that
-  // constraint, we can't make a contiguous range for the result of abs.
-  ICmpInst::Predicate AbsPred = ICmpInst::BAD_ICMP_PREDICATE;
-  Value *SP0, *SP1;
-  SelectPatternFlavor SPF = matchSelectPattern(Op0, SP0, SP1).Flavor;
-  if (SPF == SelectPatternFlavor::SPF_ABS &&
-      cast<Instruction>(SP1)->hasNoSignedWrap())
-    // The result of abs(X) is >= 0 (with nsw).
-    AbsPred = ICmpInst::ICMP_SGE;
-  if (SPF == SelectPatternFlavor::SPF_NABS)
-    // The result of -abs(X) is <= 0.
-    AbsPred = ICmpInst::ICMP_SLE;
-
-  if (AbsPred == ICmpInst::BAD_ICMP_PREDICATE)
-    return nullptr;
-
-  // If there is no intersection between abs/nabs and the range of this icmp,
-  // the icmp must be false. If the abs/nabs range is a subset of the icmp
-  // range, the icmp must be true.
-  APInt Zero = APInt::getNullValue(C->getBitWidth());
-  ConstantRange AbsRange = ConstantRange::makeExactICmpRegion(AbsPred, Zero);
-  ConstantRange CmpRange = ConstantRange::makeExactICmpRegion(Pred, *C);
-  if (AbsRange.intersectWith(CmpRange).isEmptySet())
-    return getFalse(GetCompareTy(Op0));
-  if (CmpRange.contains(AbsRange))
-    return getTrue(GetCompareTy(Op0));
-
-  return nullptr;
-}
-
 /// Simplify integer comparisons where at least one operand of the compare
 /// matches an integer min/max idiom.
 static Value *simplifyICmpWithMinMax(CmpInst::Predicate Pred, Value *LHS,
@@ -3295,9 +3257,6 @@
   if (Value *V = simplifyICmpWithMinMax(Pred, LHS, RHS, Q, MaxRecurse))
     return V;
 
-  if (Value *V = simplifyICmpWithAbsNabs(Pred, LHS, RHS))
-    return V;
-
   // Simplify comparisons of related pointers using a powerful, recursive
   // GEP-walk when we have target data available..
   if (LHS->getType()->isPointerTy())
Index: llvm/lib/Analysis/ValueTracking.cpp
===================================================================
--- llvm/lib/Analysis/ValueTracking.cpp
+++ llvm/lib/Analysis/ValueTracking.cpp
@@ -5653,6 +5653,36 @@
   }
 }
 
+static void setLimitsForSelect(const SelectInst &SI, APInt &Lower,
+                               APInt &Upper) {
+  const Value *LHS, *RHS;
+  SelectPatternResult R = matchSelectPattern(&SI, LHS, RHS);
+  if (R.Flavor == SPF_UNKNOWN)
+    return;
+
+  unsigned BitWidth = SI.getType()->getScalarSizeInBits();
+
+  // matchSelectPattern() returns the negation part of an abs pattern in RHS.
+  // If the negate has an NSW flag, abs(INT_MIN) is undefined. Without that
+  // constraint, we can't make a contiguous range for the result of abs.
+  if (R.Flavor == SelectPatternFlavor::SPF_ABS &&
+      cast<Instruction>(RHS)->hasNoSignedWrap()) {
+    // The result of abs(X) is >= 0 (with nsw).
+    Lower = APInt::getNullValue(BitWidth);
+    Upper = APInt::getSignedMaxValue(BitWidth) + 1;
+    return;
+  }
+
+  if (R.Flavor == SelectPatternFlavor::SPF_NABS) {
+    // The result of -abs(X) is <= 0.
+    Lower = APInt::getSignedMinValue(BitWidth);
+    Upper = APInt(BitWidth, 1);
+    return;
+  }
+
+  // TODO Handle min/max flavors.
+}
+
 ConstantRange llvm::computeConstantRange(const Value *V, bool UseInstrInfo) {
   assert(V->getType()->isIntOrIntVectorTy() && "Expected integer instruction");
 
@@ -5664,6 +5694,8 @@
     setLimitsForBinOp(*BO, Lower, Upper, IIQ);
   else if (auto *II = dyn_cast<IntrinsicInst>(V))
     setLimitsForIntrinsic(*II, Lower, Upper);
+  else if (auto *SI = dyn_cast<SelectInst>(V))
+    setLimitsForSelect(*SI, Lower, Upper);
 
   ConstantRange CR = Lower != Upper ? ConstantRange(Lower, Upper)
                                     : ConstantRange(BitWidth, true);