diff --git a/llvm/include/llvm/Analysis/BranchProbabilityInfo.h b/llvm/include/llvm/Analysis/BranchProbabilityInfo.h
index 28418198aceaa..51c6ef3fccd9e 100644
--- a/llvm/include/llvm/Analysis/BranchProbabilityInfo.h
+++ b/llvm/include/llvm/Analysis/BranchProbabilityInfo.h
@@ -361,12 +361,12 @@ class BranchProbabilityInfo {
   Optional<uint32_t> getEstimatedBlockWeight(const BasicBlock *BB) const;
 
   /// Returns estimated weight to enter \p L. In other words it is weight of
-  /// loop's header block not scaled by trip count. Returns None if \p L has no
-  /// no estimated weight.
+  /// loop's header block not scaled by trip count. Returns std::nullopt if \p L
+  /// has no no estimated weight.
   Optional<uint32_t> getEstimatedLoopWeight(const LoopData &L) const;
 
-  /// Return estimated weight for \p Edge. Returns None if estimated weight is
-  /// unknown.
+  /// Return estimated weight for \p Edge. Returns std::nullopt if estimated
+  /// weight is unknown.
   Optional<uint32_t> getEstimatedEdgeWeight(const LoopEdge &Edge) const;
 
   /// Iterates over all edges leading from \p SrcBB to \p Successors and
diff --git a/llvm/include/llvm/Analysis/InlineAdvisor.h b/llvm/include/llvm/Analysis/InlineAdvisor.h
index 42063ea3887c4..150ae978b2f25 100644
--- a/llvm/include/llvm/Analysis/InlineAdvisor.h
+++ b/llvm/include/llvm/Analysis/InlineAdvisor.h
@@ -293,8 +293,8 @@ getDevelopmentModeAdvisor(Module &M, ModuleAnalysisManager &MAM,
 
 /// Return the cost only if the inliner should attempt to inline at the given
 /// CallSite. If we return the cost, we will emit an optimisation remark later
-/// using that cost, so we won't do so from this function. Return None if
-/// inlining should not be attempted.
+/// using that cost, so we won't do so from this function. Return std::nullopt
+/// if inlining should not be attempted.
 Optional<InlineCost>
 shouldInline(CallBase &CB, function_ref<InlineCost(CallBase &CB)> GetInlineCost,
              OptimizationRemarkEmitter &ORE, bool EnableDeferral = true);
diff --git a/llvm/include/llvm/Analysis/LoopCacheAnalysis.h b/llvm/include/llvm/Analysis/LoopCacheAnalysis.h
index c6d4382533f48..6c5a3ad8cbc9d 100644
--- a/llvm/include/llvm/Analysis/LoopCacheAnalysis.h
+++ b/llvm/include/llvm/Analysis/LoopCacheAnalysis.h
@@ -72,7 +72,7 @@ class IndexedReference {
   /// Return true/false if the current object and the indexed reference \p Other
   /// are/aren't in the same cache line of size \p CLS. Two references are in
   /// the same chace line iff the distance between them in the innermost
-  /// dimension is less than the cache line size. Return None if unsure.
+  /// dimension is less than the cache line size. Return std::nullopt if unsure.
   Optional<bool> hasSpacialReuse(const IndexedReference &Other, unsigned CLS,
                                  AAResults &AA) const;
 
diff --git a/llvm/include/llvm/Analysis/ScalarEvolution.h b/llvm/include/llvm/Analysis/ScalarEvolution.h
index 6a2dbf79de7ac..e57a01f5d408d 100644
--- a/llvm/include/llvm/Analysis/ScalarEvolution.h
+++ b/llvm/include/llvm/Analysis/ScalarEvolution.h
@@ -537,8 +537,8 @@ class ScalarEvolution {
 
   /// Parse NSW/NUW flags from add/sub/mul IR binary operation \p Op into
   /// SCEV no-wrap flags, and deduce flag[s] that aren't known yet.
-  /// Does not mutate the original instruction. Returns None if it could not
-  /// deduce more precise flags than the instruction already has, otherwise
+  /// Does not mutate the original instruction. Returns std::nullopt if it could
+  /// not deduce more precise flags than the instruction already has, otherwise
   /// returns proven flags.
   Optional<SCEV::NoWrapFlags>
   getStrengthenedNoWrapFlagsFromBinOp(const OverflowingBinaryOperator *OBO);
diff --git a/llvm/include/llvm/Analysis/Utils/TFUtils.h b/llvm/include/llvm/Analysis/Utils/TFUtils.h
index 637641a779872..7cb72acb80d19 100644
--- a/llvm/include/llvm/Analysis/Utils/TFUtils.h
+++ b/llvm/include/llvm/Analysis/Utils/TFUtils.h
@@ -82,10 +82,10 @@ class TFModelEvaluator final {
   TFModelEvaluator(const TFModelEvaluator &) = delete;
   TFModelEvaluator(TFModelEvaluator &&) = delete;
 
-  /// Evaluate the model, assuming it is valid. Returns None if the evaluation
-  /// fails or the model is invalid, or an EvaluationResult otherwise. The
-  /// inputs are assumed to have been already provided via getInput(). When
-  /// returning None, it also invalidates this object.
+  /// Evaluate the model, assuming it is valid. Returns std::nullopt if the
+  /// evaluation fails or the model is invalid, or an EvaluationResult
+  /// otherwise. The inputs are assumed to have been already provided via
+  /// getInput(). When returning None, it also invalidates this object.
   Optional<EvaluationResult> evaluate();
 
   /// Provides access to the input vector.
diff --git a/llvm/include/llvm/CodeGen/SelectionDAG.h b/llvm/include/llvm/CodeGen/SelectionDAG.h
index 40f9a97fa3816..2af9fe4a970a0 100644
--- a/llvm/include/llvm/CodeGen/SelectionDAG.h
+++ b/llvm/include/llvm/CodeGen/SelectionDAG.h
@@ -2156,8 +2156,8 @@ class SelectionDAG {
   bool areNonVolatileConsecutiveLoads(LoadSDNode *LD, LoadSDNode *Base,
                                       unsigned Bytes, int Dist) const;
 
-  /// Infer alignment of a load / store address. Return None if it cannot be
-  /// inferred.
+  /// Infer alignment of a load / store address. Return std::nullopt if it
+  /// cannot be inferred.
   MaybeAlign InferPtrAlign(SDValue Ptr) const;
 
   /// Compute the VTs needed for the low/hi parts of a type
diff --git a/llvm/include/llvm/DebugInfo/DWARF/DWARFDebugAddr.h b/llvm/include/llvm/DebugInfo/DWARF/DWARFDebugAddr.h
index 9549a57894885..ae2a4e2276da0 100644
--- a/llvm/include/llvm/DebugInfo/DWARF/DWARFDebugAddr.h
+++ b/llvm/include/llvm/DebugInfo/DWARF/DWARFDebugAddr.h
@@ -69,7 +69,7 @@ class DWARFDebugAddrTable {
   Expected<uint64_t> getAddrEntry(uint32_t Index) const;
 
   /// Return the full length of this table, including the length field.
-  /// Return None if the length cannot be identified reliably.
+  /// Return std::nullopt if the length cannot be identified reliably.
   std::optional<uint64_t> getFullLength() const;
 
   /// Return the DWARF format of this table.
diff --git a/llvm/include/llvm/IR/DataLayout.h b/llvm/include/llvm/IR/DataLayout.h
index a6621c963d851..d607c2a766793 100644
--- a/llvm/include/llvm/IR/DataLayout.h
+++ b/llvm/include/llvm/IR/DataLayout.h
@@ -591,8 +591,8 @@ class DataLayout {
   /// the result element type and Offset to be the residual offset.
   SmallVector<APInt> getGEPIndicesForOffset(Type *&ElemTy, APInt &Offset) const;
 
-  /// Get single GEP index to access Offset inside ElemTy. Returns None if
-  /// index cannot be computed, e.g. because the type is not an aggregate.
+  /// Get single GEP index to access Offset inside ElemTy. Returns std::nullopt
+  /// if index cannot be computed, e.g. because the type is not an aggregate.
   /// ElemTy is updated to be the result element type and Offset to be the
   /// residual offset.
   Optional<APInt> getGEPIndexForOffset(Type *&ElemTy, APInt &Offset) const;
diff --git a/llvm/include/llvm/IR/DebugInfoMetadata.h b/llvm/include/llvm/IR/DebugInfoMetadata.h
index e6bfea5f124b9..534de3d72b659 100644
--- a/llvm/include/llvm/IR/DebugInfoMetadata.h
+++ b/llvm/include/llvm/IR/DebugInfoMetadata.h
@@ -1745,7 +1745,7 @@ class DILocation : public MDNode {
   /// Returns a new DILocation with duplication factor \p DF * current
   /// duplication factor encoded in the discriminator. The current duplication
   /// factor is as defined by getDuplicationFactor().
-  /// Returns None if encoding failed.
+  /// Returns std::nullopt if encoding failed.
   inline std::optional<const DILocation *>
   cloneByMultiplyingDuplicationFactor(unsigned DF) const;
 
diff --git a/llvm/include/llvm/IR/Instructions.h b/llvm/include/llvm/IR/Instructions.h
index 1afb9e50e6563..55486e5ef6477 100644
--- a/llvm/include/llvm/IR/Instructions.h
+++ b/llvm/include/llvm/IR/Instructions.h
@@ -107,8 +107,8 @@ class AllocaInst : public UnaryInstruction {
     return getType()->getAddressSpace();
   }
 
-  /// Get allocation size in bits. Returns None if size can't be determined,
-  /// e.g. in case of a VLA.
+  /// Get allocation size in bits. Returns std::nullopt if size can't be
+  /// determined, e.g. in case of a VLA.
   std::optional<TypeSize> getAllocationSizeInBits(const DataLayout &DL) const;
 
   /// Return the type that is being allocated by the instruction.
diff --git a/llvm/include/llvm/MC/MCRegisterInfo.h b/llvm/include/llvm/MC/MCRegisterInfo.h
index 40095c193fad6..520b6946db91d 100644
--- a/llvm/include/llvm/MC/MCRegisterInfo.h
+++ b/llvm/include/llvm/MC/MCRegisterInfo.h
@@ -512,8 +512,8 @@ class MCRegisterInfo {
   /// debugging info.
   int getDwarfRegNum(MCRegister RegNum, bool isEH) const;
 
-  /// Map a dwarf register back to a target register. Returns None is there is
-  /// no mapping.
+  /// Map a dwarf register back to a target register. Returns std::nullopt is
+  /// there is no mapping.
   std::optional<unsigned> getLLVMRegNum(unsigned RegNum, bool isEH) const;
 
   /// Map a target EH register number to an equivalent DWARF register
diff --git a/llvm/include/llvm/MC/MCStreamer.h b/llvm/include/llvm/MC/MCStreamer.h
index bdab8e3a3f3ae..a53435e09b4ff 100644
--- a/llvm/include/llvm/MC/MCStreamer.h
+++ b/llvm/include/llvm/MC/MCStreamer.h
@@ -1084,8 +1084,8 @@ class MCStreamer {
 
   virtual void emitSyntaxDirective();
 
-  /// Record a relocation described by the .reloc directive. Return None if
-  /// succeeded. Otherwise, return a pair (Name is invalid, error message).
+  /// Record a relocation described by the .reloc directive. Return std::nullopt
+  /// if succeeded. Otherwise, return a pair (Name is invalid, error message).
   virtual std::optional<std::pair<bool, std::string>>
   emitRelocDirective(const MCExpr &Offset, StringRef Name, const MCExpr *Expr,
                      SMLoc Loc, const MCSubtargetInfo &STI) {
diff --git a/llvm/include/llvm/Remarks/HotnessThresholdParser.h b/llvm/include/llvm/Remarks/HotnessThresholdParser.h
index f78625c35e0d3..4cd0d2dff2fe6 100644
--- a/llvm/include/llvm/Remarks/HotnessThresholdParser.h
+++ b/llvm/include/llvm/Remarks/HotnessThresholdParser.h
@@ -26,8 +26,8 @@ namespace remarks {
 // 1. integer: manually specified threshold; or
 // 2. string 'auto': automatically get threshold from profile summary.
 //
-// Return None Optional if 'auto' is specified, indicating the value will
-// be filled later during PSI.
+// Return std::nullopt Optional if 'auto' is specified, indicating the value
+// will be filled later during PSI.
 inline Expected<std::optional<uint64_t>> parseHotnessThresholdOption(StringRef Arg) {
   if (Arg == "auto")
     return std::nullopt;
diff --git a/llvm/lib/Analysis/InlineAdvisor.cpp b/llvm/lib/Analysis/InlineAdvisor.cpp
index ae57a9754c66b..97ce2d102d495 100644
--- a/llvm/lib/Analysis/InlineAdvisor.cpp
+++ b/llvm/lib/Analysis/InlineAdvisor.cpp
@@ -364,8 +364,8 @@ void llvm::setInlineRemark(CallBase &CB, StringRef Message) {
 
 /// Return the cost only if the inliner should attempt to inline at the given
 /// CallSite. If we return the cost, we will emit an optimisation remark later
-/// using that cost, so we won't do so from this function. Return None if
-/// inlining should not be attempted.
+/// using that cost, so we won't do so from this function. Return std::nullopt
+/// if inlining should not be attempted.
 Optional<InlineCost>
 llvm::shouldInline(CallBase &CB,
                    function_ref<InlineCost(CallBase &CB)> GetInlineCost,
diff --git a/llvm/lib/Analysis/InlineCost.cpp b/llvm/lib/Analysis/InlineCost.cpp
index 9a5f985acf071..ab414f67a22b5 100644
--- a/llvm/lib/Analysis/InlineCost.cpp
+++ b/llvm/lib/Analysis/InlineCost.cpp
@@ -813,8 +813,8 @@ class InlineCostCallAnalyzer final : public CallAnalyzer {
   }
 
   // Determine whether we should inline the given call site, taking into account
-  // both the size cost and the cycle savings.  Return None if we don't have
-  // suficient profiling information to determine.
+  // both the size cost and the cycle savings.  Return std::nullopt if we don't
+  // have suficient profiling information to determine.
   std::optional<bool> costBenefitAnalysis() {
     if (!CostBenefitAnalysisEnabled)
       return std::nullopt;
diff --git a/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.h b/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.h
index c12608515e64f..27438da368ffa 100644
--- a/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.h
+++ b/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.h
@@ -890,8 +890,8 @@ class MLocTracker {
   void writeRegMask(const MachineOperand *MO, unsigned CurBB, unsigned InstID);
 
   /// Find LocIdx for SpillLoc \p L, creating a new one if it's not tracked.
-  /// Returns None when in scenarios where a spill slot could be tracked, but
-  /// we would likely run into resource limitations.
+  /// Returns std::nullopt when in scenarios where a spill slot could be
+  /// tracked, but we would likely run into resource limitations.
   Optional<SpillLocationNo> getOrTrackSpillLoc(SpillLoc L);
 
   // Get LocIdx of a spill ID.
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index fcaf97d0c15a1..b63dc0594654c 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -7889,7 +7889,8 @@ struct ByteProvider {
 } // end anonymous namespace
 
 /// Recursively traverses the expression calculating the origin of the requested
-/// byte of the given value. Returns None if the provider can't be calculated.
+/// byte of the given value. Returns std::nullopt if the provider can't be
+/// calculated.
 ///
 /// For all the values except the root of the expression, we verify that the
 /// value has exactly one use and if not then return std::nullopt. This way if
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index c29261ea8bf90..76b09961b0534 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -11468,8 +11468,8 @@ bool SelectionDAG::areNonVolatileConsecutiveLoads(LoadSDNode *LD,
   return false;
 }
 
-/// InferPtrAlignment - Infer alignment of a load / store address. Return None
-/// if it cannot be inferred.
+/// InferPtrAlignment - Infer alignment of a load / store address. Return
+/// std::nullopt if it cannot be inferred.
 MaybeAlign SelectionDAG::InferPtrAlign(SDValue Ptr) const {
   // If this is a GlobalAddress + cst, return the alignment.
   const GlobalValue *GV = nullptr;
diff --git a/llvm/lib/DebugInfo/Symbolize/MarkupFilter.cpp b/llvm/lib/DebugInfo/Symbolize/MarkupFilter.cpp
index a899bba244045..f0681d9dd8566 100644
--- a/llvm/lib/DebugInfo/Symbolize/MarkupFilter.cpp
+++ b/llvm/lib/DebugInfo/Symbolize/MarkupFilter.cpp
@@ -493,7 +493,7 @@ void MarkupFilter::printValue(Twine Value) {
 
 // This macro helps reduce the amount of indirection done through Optional
 // below, since the usual case upon returning a std::nullopt Optional is to
-// return None.
+// return std::nullopt.
 #define ASSIGN_OR_RETURN_NONE(TYPE, NAME, EXPR)                                \
   auto NAME##Opt = (EXPR);                                                     \
   if (!NAME##Opt)                                                              \
diff --git a/llvm/lib/IR/DebugInfo.cpp b/llvm/lib/IR/DebugInfo.cpp
index dcdab1d39a093..5375edcf42f90 100644
--- a/llvm/lib/IR/DebugInfo.cpp
+++ b/llvm/lib/IR/DebugInfo.cpp
@@ -1746,7 +1746,7 @@ void at::deleteAll(Function *F) {
 }
 
 /// Collect constant properies (base, size, offset) of \p StoreDest.
-/// Return None if any properties are not constants.
+/// Return std::nullopt if any properties are not constants.
 static std::optional<AssignmentInfo>
 getAssignmentInfoImpl(const DataLayout &DL, const Value *StoreDest,
                       uint64_t SizeInBits) {
diff --git a/llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp b/llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp
index 8d2a7f1e00ff1..ac26f1a43a70d 100644
--- a/llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp
+++ b/llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp
@@ -85,8 +85,8 @@ static bool isScalarMoveInstr(const MachineInstr &MI) {
   }
 }
 
-/// Get the EEW for a load or store instruction.  Return None if MI is not
-/// a load or store which ignores SEW.
+/// Get the EEW for a load or store instruction.  Return std::nullopt if MI is
+/// not a load or store which ignores SEW.
 static std::optional<unsigned> getEEWForLoadStore(const MachineInstr &MI) {
   switch (getRVVMCOpcode(MI.getOpcode())) {
   default:
diff --git a/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp b/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp
index 467ab7fe2a556..2dbd64a16928d 100644
--- a/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp
+++ b/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp
@@ -476,8 +476,8 @@ static bool findArgParts(Argument *Arg, const DataLayout &DL, AAResults &AAR,
   bool AreStoresAllowed = Arg->getParamByValType() && Arg->getParamAlign();
 
   // An end user of a pointer argument is a load or store instruction.
-  // Returns None if this load or store is not based on the argument. Return
-  // true if we can promote the instruction, false otherwise.
+  // Returns std::nullopt if this load or store is not based on the argument.
+  // Return true if we can promote the instruction, false otherwise.
   auto HandleEndUser = [&](auto *I, Type *Ty,
                            bool GuaranteedToExecute) -> Optional<bool> {
     // Don't promote volatile or atomic instructions.
diff --git a/llvm/lib/Transforms/Scalar/Float2Int.cpp b/llvm/lib/Transforms/Scalar/Float2Int.cpp
index 432d53ec9759c..30967cc5efa9d 100644
--- a/llvm/lib/Transforms/Scalar/Float2Int.cpp
+++ b/llvm/lib/Transforms/Scalar/Float2Int.cpp
@@ -235,7 +235,7 @@ void Float2IntPass::walkBackwards() {
 }
 
 // Calculate result range from operand ranges.
-// Return None if the range cannot be calculated yet.
+// Return std::nullopt if the range cannot be calculated yet.
 Optional<ConstantRange> Float2IntPass::calcRange(Instruction *I) {
   SmallVector<ConstantRange, 4> OpRanges;
   for (Value *O : I->operands()) {
diff --git a/llvm/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp b/llvm/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp
index 6e5a4153e7883..cf94818704bd6 100644
--- a/llvm/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp
+++ b/llvm/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp
@@ -554,7 +554,7 @@ class LoopConstrainer {
 
   // Compute a safe set of limits for the main loop to run in -- effectively the
   // intersection of `Range' and the iteration space of the original loop.
-  // Return None if unable to compute the set of subranges.
+  // Return std::nullopt if unable to compute the set of subranges.
   Optional<SubRanges> calculateSubRanges(bool IsSignedPredicate) const;
 
   // Clone `OriginalLoop' and return the result in CLResult.  The IR after
diff --git a/llvm/lib/Transforms/Utils/CodeMoverUtils.cpp b/llvm/lib/Transforms/Utils/CodeMoverUtils.cpp
index 53d09adcc251c..2ff5aec8f8496 100644
--- a/llvm/lib/Transforms/Utils/CodeMoverUtils.cpp
+++ b/llvm/lib/Transforms/Utils/CodeMoverUtils.cpp
@@ -58,8 +58,8 @@ class ControlConditions {
 public:
   /// Return a ControlConditions which stores all conditions required to execute
   /// \p BB from \p Dominator. If \p MaxLookup is non-zero, it limits the
-  /// number of conditions to collect. Return None if not all conditions are
-  /// collected successfully, or we hit the limit.
+  /// number of conditions to collect. Return std::nullopt if not all conditions
+  /// are collected successfully, or we hit the limit.
   static const Optional<ControlConditions>
   collectControlConditions(const BasicBlock &BB, const BasicBlock &Dominator,
                            const DominatorTree &DT,
diff --git a/llvm/lib/Transforms/Utils/ValueMapper.cpp b/llvm/lib/Transforms/Utils/ValueMapper.cpp
index 074af66282d41..8b3ffb1d8cebb 100644
--- a/llvm/lib/Transforms/Utils/ValueMapper.cpp
+++ b/llvm/lib/Transforms/Utils/ValueMapper.cpp
@@ -271,7 +271,8 @@ class MDNodeMapper {
   /// return the result of \a mapDistinctNode().
   ///
   /// \return std::nullopt if \c Op is an unmapped uniqued \a MDNode.
-  /// \post getMappedOp(Op) only returns std::nullopt if this returns None.
+  /// \post getMappedOp(Op) only returns std::nullopt if this returns
+  /// std::nullopt.
   Optional<Metadata *> tryToMapOperand(const Metadata *Op);
 
   /// Map a distinct node.
diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index 9f6718b32f571..6ba0185f0ab01 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -402,7 +402,7 @@ static Constant *getSignedIntOrFpConstant(Type *Ty, int64_t C) {
 ///   1) Returns exact trip count if it is known.
 ///   2) Returns expected trip count according to profile data if any.
 ///   3) Returns upper bound estimate if it is known.
-///   4) Returns None if all of the above failed.
+///   4) Returns std::nullopt if all of the above failed.
 static Optional<unsigned> getSmallBestKnownTC(ScalarEvolution &SE, Loop *L) {
   // Check if exact trip count is known.
   if (unsigned ExpectedTC = SE.getSmallConstantTripCount(L))
diff --git a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
index 27d0b18638a1c..8aa4f3de3976e 100644
--- a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -2139,9 +2139,9 @@ class BoUpSLP {
 
   /// Evaluate each pair in \p Candidates and return index into \p Candidates
   /// for a pair which have highest score deemed to have best chance to form
-  /// root of profitable tree to vectorize. Return None if no candidate scored
-  /// above the LookAheadHeuristics::ScoreFail.
-  /// \param Limit Lower limit of the cost, considered to be good enough score.
+  /// root of profitable tree to vectorize. Return std::nullopt if no candidate
+  /// scored above the LookAheadHeuristics::ScoreFail. \param Limit Lower limit
+  /// of the cost, considered to be good enough score.
   Optional<int>
   findBestRootPair(ArrayRef<std::pair<Value *, Value *>> Candidates,
                    int Limit = LookAheadHeuristics::ScoreFail) {
diff --git a/llvm/tools/llvm-objdump/llvm-objdump.cpp b/llvm/tools/llvm-objdump/llvm-objdump.cpp
index 228e094f53550..422e6e5ab9c45 100644
--- a/llvm/tools/llvm-objdump/llvm-objdump.cpp
+++ b/llvm/tools/llvm-objdump/llvm-objdump.cpp
@@ -1271,7 +1271,7 @@ static void createFakeELFSections(ObjectFile &Obj) {
 }
 
 // Tries to fetch a more complete version of the given object file using its
-// Build ID. Returns None if nothing was found.
+// Build ID. Returns std::nullopt if nothing was found.
 static std::optional<OwningBinary<Binary>>
 fetchBinaryByBuildID(const ObjectFile &Obj) {
   std::optional<object::BuildIDRef> BuildID = getBuildID(&Obj);
diff --git a/llvm/tools/llvm-readobj/ELFDumper.cpp b/llvm/tools/llvm-readobj/ELFDumper.cpp
index d3357f5679edb..7d2b557efd9b3 100644
--- a/llvm/tools/llvm-readobj/ELFDumper.cpp
+++ b/llvm/tools/llvm-readobj/ELFDumper.cpp
@@ -306,8 +306,8 @@ template <typename ELFT> class ELFDumper : public ObjDumper {
 
   // Returns the function symbol index for the given address. Matches the
   // symbol's section with FunctionSec when specified.
-  // Returns None if no function symbol can be found for the address or in case
-  // it is not defined in the specified section.
+  // Returns std::nullopt if no function symbol can be found for the address or
+  // in case it is not defined in the specified section.
   SmallVector<uint32_t>
   getSymbolIndexesForFunctionAddress(uint64_t SymValue,
                                      Optional<const Elf_Shdr *> FunctionSec);
diff --git a/llvm/utils/TableGen/GlobalISelEmitter.cpp b/llvm/utils/TableGen/GlobalISelEmitter.cpp
index d253417e7c25b..c908107f5bd56 100644
--- a/llvm/utils/TableGen/GlobalISelEmitter.cpp
+++ b/llvm/utils/TableGen/GlobalISelEmitter.cpp
@@ -3691,7 +3691,7 @@ class GlobalISelEmitter {
   inferSubRegIndexForNode(TreePatternNode *SubRegIdxNode);
 
   /// Infer a CodeGenRegisterClass which suppoorts \p Ty and \p SubRegIdxNode.
-  /// Return None if no such class exists.
+  /// Return std::nullopt if no such class exists.
   Optional<const CodeGenRegisterClass *>
   inferSuperRegisterClass(const TypeSetByHwMode &Ty,
                           TreePatternNode *SubRegIdxNode);
@@ -3700,8 +3700,8 @@ class GlobalISelEmitter {
   Optional<const CodeGenRegisterClass *>
   getRegClassFromLeaf(TreePatternNode *Leaf);
 
-  /// Return a CodeGenRegisterClass for \p N if one can be found. Return None
-  /// otherwise.
+  /// Return a CodeGenRegisterClass for \p N if one can be found. Return
+  /// std::nullopt otherwise.
   Optional<const CodeGenRegisterClass *>
   inferRegClassFromPattern(TreePatternNode *N);