diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 3b9aa9ab623f8..9808308cbfed9 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -10483,15 +10483,9 @@ ScalarEvolution::ExitLimit ScalarEvolution::howFarToZero(const SCEV *V,
   // Get the initial value for the loop.
   const SCEV *Start = getSCEVAtScope(AddRec->getStart(), L->getParentLoop());
   const SCEV *Step = getSCEVAtScope(AddRec->getOperand(1), L->getParentLoop());
-
-  // For now we handle only constant steps.
-  //
-  // TODO: Handle a nonconstant Step given AddRec<NUW>. If the
-  // AddRec is NUW, then (in an unsigned sense) it cannot be counting up to wrap
-  // to 0, it must be counting down to equal 0. Consequently, N = Start / -Step.
-  // We have not yet seen any such cases.
   const SCEVConstant *StepC = dyn_cast<SCEVConstant>(Step);
-  if (!StepC || StepC->getValue()->isZero())
+
+  if (!isLoopInvariant(Step, L) || !isKnownNonZero(Step))
     return getCouldNotCompute();
 
   // For positive steps (counting up until unsigned overflow):
@@ -10499,13 +10493,16 @@ ScalarEvolution::ExitLimit ScalarEvolution::howFarToZero(const SCEV *V,
   // For negative steps (counting down to zero):
   //   N = Start/-Step
   // First compute the unsigned distance from zero in the direction of Step.
-  bool CountDown = StepC->getAPInt().isNegative();
-  const SCEV *Distance = CountDown ? Start : getNegativeSCEV(Start);
+  bool CountDown = isKnownNegative(Step);
+  if (!CountDown && !isKnownNonNegative(Step))
+    return getCouldNotCompute();
 
+  const SCEV *Distance = CountDown ? Start : getNegativeSCEV(Start);
   // Handle unitary steps, which cannot wraparound.
   // 1*N = -Start; -1*N = Start (mod 2^BW), so:
   //   N = Distance (as unsigned)
-  if (StepC->getValue()->isOne() || StepC->getValue()->isMinusOne()) {
+  if (StepC &&
+      (StepC->getValue()->isOne() || StepC->getValue()->isMinusOne())) {
     APInt MaxBECount = getUnsignedRangeMax(applyLoopGuards(Distance, L));
     MaxBECount = APIntOps::umin(MaxBECount, getUnsignedRangeMax(Distance));
 
@@ -10550,6 +10547,8 @@ ScalarEvolution::ExitLimit ScalarEvolution::howFarToZero(const SCEV *V,
   }
 
   // Solve the general equation.
+  if (!StepC)
+    return getCouldNotCompute();
   const SCEV *E = SolveLinEquationWithOverflow(StepC->getAPInt(),
                                                getNegativeSCEV(Start), *this);
 
diff --git a/llvm/test/Analysis/ScalarEvolution/scalable-vector.ll b/llvm/test/Analysis/ScalarEvolution/scalable-vector.ll
index 81434d1bf064c..0a3ec4d66301b 100644
--- a/llvm/test/Analysis/ScalarEvolution/scalable-vector.ll
+++ b/llvm/test/Analysis/ScalarEvolution/scalable-vector.ll
@@ -91,13 +91,14 @@ define void @vscale_step_ne_tripcount(i64 %N) vscale_range(2, 1024) {
 ; CHECK-NEXT:    %n.vec = sub i64 %n.rnd.up, %n.mod.vf
 ; CHECK-NEXT:    --> (4 * vscale * ((-1 + (4 * vscale)<nuw><nsw> + %N) /u (4 * vscale)<nuw><nsw>)) U: [0,-3) S: [-9223372036854775808,9223372036854775805)
 ; CHECK-NEXT:    %index = phi i64 [ 0, %vector.ph ], [ %index.next, %vector.body ]
-; CHECK-NEXT:    --> {0,+,(4 * vscale)<nuw><nsw>}<nuw><%vector.body> U: [0,-3) S: [-9223372036854775808,9223372036854775805) Exits: <<Unknown>> LoopDispositions: { %vector.body: Computable }
+; CHECK-NEXT:    --> {0,+,(4 * vscale)<nuw><nsw>}<nuw><%vector.body> U: [0,-3) S: [-9223372036854775808,9223372036854775805) Exits: (4 * vscale * ((-1 * vscale * (4 + (-4 * ((-1 + (4 * vscale)<nuw><nsw> + %N) /u (4 * vscale)<nuw><nsw>))<nsw>)<nsw>) /u (4 * vscale)<nuw><nsw>)) LoopDispositions: { %vector.body: Computable }
 ; CHECK-NEXT:    %index.next = add nuw i64 %index, %2
-; CHECK-NEXT:    --> {(4 * vscale)<nuw><nsw>,+,(4 * vscale)<nuw><nsw>}<nuw><%vector.body> U: [8,-3) S: [-9223372036854775808,9223372036854775805) Exits: <<Unknown>> LoopDispositions: { %vector.body: Computable }
+; CHECK-NEXT:    --> {(4 * vscale)<nuw><nsw>,+,(4 * vscale)<nuw><nsw>}<nuw><%vector.body> U: [8,-3) S: [-9223372036854775808,9223372036854775805) Exits: (vscale * (4 + (4 * ((-1 * vscale * (4 + (-4 * ((-1 + (4 * vscale)<nuw><nsw> + %N) /u (4 * vscale)<nuw><nsw>))<nsw>)<nsw>) /u (4 * vscale)<nuw><nsw>))<nuw><nsw>)<nuw>) LoopDispositions: { %vector.body: Computable }
 ; CHECK-NEXT:  Determining loop execution counts for: @vscale_step_ne_tripcount
-; CHECK-NEXT:  Loop %vector.body: Unpredictable backedge-taken count.
-; CHECK-NEXT:  Loop %vector.body: Unpredictable constant max backedge-taken count.
-; CHECK-NEXT:  Loop %vector.body: Unpredictable symbolic max backedge-taken count.
+; CHECK-NEXT:  Loop %vector.body: backedge-taken count is ((-1 * vscale * (4 + (-4 * ((-1 + (4 * vscale)<nuw><nsw> + %N) /u (4 * vscale)<nuw><nsw>))<nsw>)<nsw>) /u (4 * vscale)<nuw><nsw>)
+; CHECK-NEXT:  Loop %vector.body: constant max backedge-taken count is i64 2305843009213693951
+; CHECK-NEXT:  Loop %vector.body: symbolic max backedge-taken count is ((-1 * vscale * (4 + (-4 * ((-1 + (4 * vscale)<nuw><nsw> + %N) /u (4 * vscale)<nuw><nsw>))<nsw>)<nsw>) /u (4 * vscale)<nuw><nsw>)
+; CHECK-NEXT:  Loop %vector.body: Trip multiple is 1
 ;
 entry:
   %0 = sub i64 -1, %N