diff --git a/llvm/lib/CodeGen/AssignmentTrackingAnalysis.cpp b/llvm/lib/CodeGen/AssignmentTrackingAnalysis.cpp
index 6c222e159419e..ffdf08eec9963 100644
--- a/llvm/lib/CodeGen/AssignmentTrackingAnalysis.cpp
+++ b/llvm/lib/CodeGen/AssignmentTrackingAnalysis.cpp
@@ -2780,7 +2780,6 @@ removeUndefDbgLocsFromEntryBlock(const BasicBlock *BB,
   };
 
   bool Changed = false;
-  DenseMap<DebugVariable, std::pair<Value *, DIExpression *>> VariableMap;
 
   // Scan over the entire block, not just over the instructions mapped by
   // FnVarLocs, because wedges in FnVarLocs may only be separated by debug
diff --git a/llvm/lib/CodeGen/BranchRelaxation.cpp b/llvm/lib/CodeGen/BranchRelaxation.cpp
index fbdc784c928c2..2d50167faa085 100644
--- a/llvm/lib/CodeGen/BranchRelaxation.cpp
+++ b/llvm/lib/CodeGen/BranchRelaxation.cpp
@@ -559,7 +559,6 @@ bool BranchRelaxation::fixupConditionalBranch(MachineInstr &MI) {
 
 bool BranchRelaxation::fixupUnconditionalBranch(MachineInstr &MI) {
   MachineBasicBlock *MBB = MI.getParent();
-  SmallVector<MachineOperand, 4> Cond;
   unsigned OldBrSize = TII->getInstSizeInBytes(MI);
   MachineBasicBlock *DestBB = TII->getBranchDestBlock(MI);
 
diff --git a/llvm/lib/CodeGen/ComplexDeinterleavingPass.cpp b/llvm/lib/CodeGen/ComplexDeinterleavingPass.cpp
index 790edf12b46be..f4fe0b3970d4c 100644
--- a/llvm/lib/CodeGen/ComplexDeinterleavingPass.cpp
+++ b/llvm/lib/CodeGen/ComplexDeinterleavingPass.cpp
@@ -1637,7 +1637,6 @@ bool ComplexDeinterleavingGraph::collectPotentialReductions(BasicBlock *B) {
   if (Br->getSuccessor(0) != B && Br->getSuccessor(1) != B)
     return false;
 
-  SmallVector<PHINode *> PHIs;
   for (auto &PHI : B->phis()) {
     if (PHI.getNumIncomingValues() != 2)
       continue;
@@ -1806,7 +1805,6 @@ bool ComplexDeinterleavingGraph::checkNodes() {
   }
 
   // Find instructions that have users outside of chain
-  SmallVector<Instruction *, 2> OuterInstructions;
   for (auto *I : AllInstructions) {
     // Skip root nodes
     if (RootToNode.count(I))
diff --git a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
index 4052060271331..a7e730eeff5ab 100644
--- a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -2060,7 +2060,6 @@ void LegalizerHelper::moreElementsVectorDst(MachineInstr &MI, LLT WideTy,
 void LegalizerHelper::moreElementsVectorSrc(MachineInstr &MI, LLT MoreTy,
                                             unsigned OpIdx) {
   MachineOperand &MO = MI.getOperand(OpIdx);
-  SmallVector<Register, 8> Regs;
   MO.setReg(MIRBuilder.buildPadVectorWithUndefElements(MoreTy, MO).getReg(0));
 }
 
@@ -2151,7 +2150,6 @@ LegalizerHelper::widenScalarMergeValues(MachineInstr &MI, unsigned TypeIdx,
   const int GCD = std::gcd(SrcSize, WideSize);
   LLT GCDTy = LLT::scalar(GCD);
 
-  SmallVector<Register, 8> Parts;
   SmallVector<Register, 8> NewMergeRegs;
   SmallVector<Register, 8> Unmerges;
   LLT WideDstTy = LLT::scalar(NumMerge * WideSize);
@@ -6644,7 +6642,6 @@ LegalizerHelper::narrowScalarExtract(MachineInstr &MI, unsigned TypeIdx,
   int NumParts = SizeOp1 / NarrowSize;
 
   SmallVector<Register, 2> SrcRegs, DstRegs;
-  SmallVector<uint64_t, 2> Indexes;
   extractParts(MI.getOperand(1).getReg(), NarrowTy, NumParts, SrcRegs,
                MIRBuilder, MRI);
 
@@ -6704,7 +6701,6 @@ LegalizerHelper::narrowScalarInsert(MachineInstr &MI, unsigned TypeIdx,
     return UnableToLegalize;
 
   SmallVector<Register, 2> SrcRegs, LeftoverRegs, DstRegs;
-  SmallVector<uint64_t, 2> Indexes;
   LLT RegTy = MRI.getType(MI.getOperand(0).getReg());
   LLT LeftoverTy;
   extractParts(MI.getOperand(1).getReg(), RegTy, NarrowTy, LeftoverTy, SrcRegs,
diff --git a/llvm/lib/CodeGen/LiveDebugVariables.cpp b/llvm/lib/CodeGen/LiveDebugVariables.cpp
index 36e53c83bcfc1..f12f437c493e1 100644
--- a/llvm/lib/CodeGen/LiveDebugVariables.cpp
+++ b/llvm/lib/CodeGen/LiveDebugVariables.cpp
@@ -1127,7 +1127,6 @@ void UserValue::computeIntervals(MachineRegisterInfo &MRI,
     SlotIndex Idx = Defs[i].first;
     DbgVariableValue DbgValue = Defs[i].second;
     SmallDenseMap<unsigned, std::pair<LiveRange *, const VNInfo *>> LIs;
-    SmallVector<const VNInfo *, 4> VNIs;
     bool ShouldExtendDef = false;
     for (unsigned LocNo : DbgValue.loc_nos()) {
       const MachineOperand &LocMO = locations[LocNo];
diff --git a/llvm/lib/CodeGen/ModuloSchedule.cpp b/llvm/lib/CodeGen/ModuloSchedule.cpp
index f028f01c58290..0f742c46fd1b3 100644
--- a/llvm/lib/CodeGen/ModuloSchedule.cpp
+++ b/llvm/lib/CodeGen/ModuloSchedule.cpp
@@ -887,7 +887,6 @@ void ModuloScheduleExpander::addBranches(MachineBasicBlock &PreheaderBB,
 
   // Start from the blocks connected to the kernel and work "out"
   // to the first prolog and the last epilog blocks.
-  SmallVector<MachineInstr *, 4> PrevInsts;
   unsigned MaxIter = PrologBBs.size() - 1;
   for (unsigned i = 0, j = MaxIter; i <= MaxIter; ++i, --j) {
     // Add branches to the prolog that go to the corresponding
@@ -2590,7 +2589,6 @@ void ModuloScheduleExpanderMVE::generateKernel(
   SmallVector<ValueMapTy> PhiVRMap;
   PhiVRMap.resize(NumUnroll);
   DenseMap<MachineInstr *, std::pair<int, int>> NewMIMap;
-  DenseMap<MachineInstr *, MachineInstr *> MIMapLastStage0;
   for (int UnrollNum = 0; UnrollNum < NumUnroll; ++UnrollNum) {
     for (MachineInstr *MI : Schedule.getInstructions()) {
       if (MI->isPHI())
diff --git a/llvm/lib/CodeGen/RemoveLoadsIntoFakeUses.cpp b/llvm/lib/CodeGen/RemoveLoadsIntoFakeUses.cpp
index 042fc13090ef6..0c05473c7449b 100644
--- a/llvm/lib/CodeGen/RemoveLoadsIntoFakeUses.cpp
+++ b/llvm/lib/CodeGen/RemoveLoadsIntoFakeUses.cpp
@@ -120,7 +120,6 @@ bool RemoveLoadsIntoFakeUses::run(MachineFunction &MF) {
 
   SmallVector<MachineInstr *> RegFakeUses;
   LivePhysRegs.init(*TRI);
-  SmallVector<MachineInstr *, 16> Statepoints;
   for (MachineBasicBlock *MBB : post_order(&MF)) {
     RegFakeUses.clear();
     LivePhysRegs.addLiveOuts(*MBB);
@@ -152,7 +151,6 @@ bool RemoveLoadsIntoFakeUses::run(MachineFunction &MF) {
         // choose to ignore it so that this pass has no side effects unrelated
         // to fake uses.
         SmallDenseSet<MachineInstr *> FakeUsesToDelete;
-        SmallVector<MachineInstr *> RemainingFakeUses;
         for (MachineInstr *&FakeUse : reverse(RegFakeUses)) {
           if (FakeUse->readsRegister(Reg, TRI)) {
             FakeUsesToDelete.insert(FakeUse);
diff --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index 6930b54ddb14a..083173daae982 100644
--- a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -6783,7 +6783,7 @@ TargetLowering::prepareUREMEqFold(EVT SETCCVT, SDValue REMNode,
   bool HadEvenDivisor = false;
   bool AllDivisorsArePowerOfTwo = true;
   bool HadTautologicalInvertedLanes = false;
-  SmallVector<SDValue, 16> PAmts, KAmts, QAmts, IAmts;
+  SmallVector<SDValue, 16> PAmts, KAmts, QAmts;
 
   auto BuildUREMPattern = [&](ConstantSDNode *CDiv, ConstantSDNode *CCmp) {
     // Division by 0 is UB. Leave it to be constant-folded elsewhere.