Index: llvm/include/llvm/Transforms/Utils/ScalarEvolutionExpander.h
===================================================================
--- llvm/include/llvm/Transforms/Utils/ScalarEvolutionExpander.h
+++ llvm/include/llvm/Transforms/Utils/ScalarEvolutionExpander.h
@@ -235,7 +235,7 @@
       return true; // by always claiming to be high-cost.
     SmallVector<SCEVOperand, 8> Worklist;
     SmallPtrSet<const SCEV *, 8> Processed;
-    int BudgetRemaining = Budget * TargetTransformInfo::TCC_Basic;
+    unsigned BudgetRemaining = Budget * TargetTransformInfo::TCC_Basic;
     Worklist.emplace_back(-1, -1, Expr);
     while (!Worklist.empty()) {
       const SCEVOperand WorkItem = Worklist.pop_back_val();
@@ -409,7 +409,7 @@
   /// Recursive helper function for isHighCostExpansion.
   bool isHighCostExpansionHelper(
     const SCEVOperand &WorkItem, Loop *L, const Instruction &At,
-    int &BudgetRemaining, const TargetTransformInfo &TTI,
+    unsigned &BudgetRemaining, const TargetTransformInfo &TTI,
     SmallPtrSetImpl<const SCEV *> &Processed,
     SmallVectorImpl<SCEVOperand> &Worklist);
 
Index: llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
===================================================================
--- llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
+++ llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
@@ -2199,7 +2199,7 @@
   return None;
 }
 
-template<typename T> static int costAndCollectOperands(
+template<typename T> static unsigned costAndCollectOperands(
   const SCEVOperand &WorkItem, const TargetTransformInfo &TTI,
   TargetTransformInfo::TargetCostKind CostKind,
   SmallVectorImpl<SCEVOperand> &Worklist) {
@@ -2340,12 +2340,9 @@
 
 bool SCEVExpander::isHighCostExpansionHelper(
     const SCEVOperand &WorkItem, Loop *L, const Instruction &At,
-    int &BudgetRemaining, const TargetTransformInfo &TTI,
+    unsigned &BudgetRemaining, const TargetTransformInfo &TTI,
     SmallPtrSetImpl<const SCEV *> &Processed,
     SmallVectorImpl<SCEVOperand> &Worklist) {
-  if (BudgetRemaining < 0)
-    return true; // Already run out of budget, give up.
-
   const SCEV *S = WorkItem.S;
   // Was the cost of expansion of this expression already accounted for?
   if (!isa<SCEVConstant>(S) && !Processed.insert(S).second)
@@ -2361,6 +2358,17 @@
           ? TargetTransformInfo::TCK_CodeSize
           : TargetTransformInfo::TCK_RecipThroughput;
 
+  // Convenience function to subtract from budget. Returns 'true'
+  // if the budget would be exceeded.
+  auto SubtractFromBudget = [](unsigned &BudgetRemaining,
+                               const unsigned &Cost) -> bool {
+    if (Cost > BudgetRemaining)
+      return true;
+
+    BudgetRemaining -= Cost;
+    return false;
+  };
+
   switch (S->getSCEVType()) {
   case scCouldNotCompute:
     llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!");
@@ -2373,18 +2381,17 @@
       return 0;
     const APInt &Imm = cast<SCEVConstant>(S)->getAPInt();
     Type *Ty = S->getType();
-    BudgetRemaining -= TTI.getIntImmCostInst(
+    unsigned Cost = TTI.getIntImmCostInst(
         WorkItem.ParentOpcode, WorkItem.OperandIdx, Imm, Ty, CostKind);
-    return BudgetRemaining < 0;
+    return SubtractFromBudget(BudgetRemaining, Cost);
   }
   case scTruncate:
   case scPtrToInt:
   case scZeroExtend:
   case scSignExtend: {
-    int Cost =
+    unsigned Cost =
         costAndCollectOperands<SCEVCastExpr>(WorkItem, TTI, CostKind, Worklist);
-    BudgetRemaining -= Cost;
-    return false; // Will answer upon next entry into this function.
+    return SubtractFromBudget(BudgetRemaining, Cost);
   }
   case scUDivExpr: {
     // UDivExpr is very likely a UDiv that ScalarEvolution's HowFarToZero or
@@ -2399,11 +2406,9 @@
             SE.getAddExpr(S, SE.getConstant(S->getType(), 1)), &At, L))
       return false; // Consider it to be free.
 
-    int Cost =
+    unsigned Cost =
         costAndCollectOperands<SCEVUDivExpr>(WorkItem, TTI, CostKind, Worklist);
-    // Need to count the cost of this UDiv.
-    BudgetRemaining -= Cost;
-    return false; // Will answer upon next entry into this function.
+    return SubtractFromBudget(BudgetRemaining, Cost);
   }
   case scAddExpr:
   case scMulExpr:
@@ -2415,17 +2420,16 @@
            "Nary expr should have more than 1 operand.");
     // The simple nary expr will require one less op (or pair of ops)
     // than the number of it's terms.
-    int Cost =
+    unsigned Cost =
         costAndCollectOperands<SCEVNAryExpr>(WorkItem, TTI, CostKind, Worklist);
-    BudgetRemaining -= Cost;
-    return BudgetRemaining < 0;
+    return SubtractFromBudget(BudgetRemaining, Cost);
   }
   case scAddRecExpr: {
     assert(cast<SCEVAddRecExpr>(S)->getNumOperands() >= 2 &&
            "Polynomial should be at least linear");
-    BudgetRemaining -= costAndCollectOperands<SCEVAddRecExpr>(
+    unsigned Cost = costAndCollectOperands<SCEVAddRecExpr>(
         WorkItem, TTI, CostKind, Worklist);
-    return BudgetRemaining < 0;
+    return SubtractFromBudget(BudgetRemaining, Cost);
   }
   }
   llvm_unreachable("Unknown SCEV kind!");