diff --git a/llvm/include/llvm/CodeGen/LiveIntervals.h b/llvm/include/llvm/CodeGen/LiveIntervals.h
index 1050b3daa0f57..c252f9d99f2af 100644
--- a/llvm/include/llvm/CodeGen/LiveIntervals.h
+++ b/llvm/include/llvm/CodeGen/LiveIntervals.h
@@ -229,8 +229,8 @@ class LiveIntervals {
   /// doing something wrong if you call pruneValue directly on a
   /// LiveInterval. Indeed, you are supposed to call pruneValue on the main
   /// LiveRange and all the LiveRanges of the subranges if any.
-  LLVM_ATTRIBUTE_UNUSED void pruneValue(LiveInterval &, SlotIndex,
-                                        SmallVectorImpl<SlotIndex> *) {
+  [[maybe_unused]] void pruneValue(LiveInterval &, SlotIndex,
+                                   SmallVectorImpl<SlotIndex> *) {
     llvm_unreachable(
         "Use pruneValue on the main LiveRange and on each subrange");
   }
diff --git a/llvm/lib/Analysis/MemorySSA.cpp b/llvm/lib/Analysis/MemorySSA.cpp
index ab373386da579..0b2e3fcfd76df 100644
--- a/llvm/lib/Analysis/MemorySSA.cpp
+++ b/llvm/lib/Analysis/MemorySSA.cpp
@@ -393,7 +393,7 @@ static bool isUseTriviallyOptimizableToLiveOnEntry(AliasAnalysisType &AA,
 /// \param AA        The AliasAnalysis we used for our search.
 /// \param AllowImpreciseClobber Always false, unless we do relaxed verify.
 
-LLVM_ATTRIBUTE_UNUSED static void
+[[maybe_unused]] static void
 checkClobberSanity(const MemoryAccess *Start, MemoryAccess *ClobberAt,
                    const MemoryLocation &StartLoc, const MemorySSA &MSSA,
                    const UpwardsMemoryQuery &Query, BatchAAResults &AA,
diff --git a/llvm/lib/CodeGen/AtomicExpandPass.cpp b/llvm/lib/CodeGen/AtomicExpandPass.cpp
index 4931403ab83a1..53f1cfe24a68d 100644
--- a/llvm/lib/CodeGen/AtomicExpandPass.cpp
+++ b/llvm/lib/CodeGen/AtomicExpandPass.cpp
@@ -770,7 +770,7 @@ struct PartwordMaskValues {
   Value *Inv_Mask = nullptr;
 };
 
-LLVM_ATTRIBUTE_UNUSED
+[[maybe_unused]]
 raw_ostream &operator<<(raw_ostream &O, const PartwordMaskValues &PMV) {
   auto PrintObj = [&O](auto *V) {
     if (V)
diff --git a/llvm/lib/CodeGen/GlobalISel/GISelValueTracking.cpp b/llvm/lib/CodeGen/GlobalISel/GISelValueTracking.cpp
index 3812823f9fffa..b630e235a7828 100644
--- a/llvm/lib/CodeGen/GlobalISel/GISelValueTracking.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/GISelValueTracking.cpp
@@ -112,7 +112,7 @@ APInt GISelValueTracking::getKnownOnes(Register R) {
   return getKnownBits(R).One;
 }
 
-LLVM_ATTRIBUTE_UNUSED static void
+[[maybe_unused]] static void
 dumpResult(const MachineInstr &MI, const KnownBits &Known, unsigned Depth) {
   dbgs() << "[" << Depth << "] Compute known bits: " << MI << "[" << Depth
          << "] Computed for: " << MI << "[" << Depth << "] Known: 0x"
diff --git a/llvm/lib/CodeGen/ScheduleDAGInstrs.cpp b/llvm/lib/CodeGen/ScheduleDAGInstrs.cpp
index 3268c267fc798..9662511e584c0 100644
--- a/llvm/lib/CodeGen/ScheduleDAGInstrs.cpp
+++ b/llvm/lib/CodeGen/ScheduleDAGInstrs.cpp
@@ -1551,7 +1551,7 @@ LLVM_DUMP_METHOD void ILPValue::dump() const {
   dbgs() << *this << '\n';
 }
 
-LLVM_ATTRIBUTE_UNUSED
+[[maybe_unused]]
 raw_ostream &llvm::operator<<(raw_ostream &OS, const ILPValue &Val) {
   Val.print(OS);
   return OS;
diff --git a/llvm/lib/Support/TextEncoding.cpp b/llvm/lib/Support/TextEncoding.cpp
index 804ff07f6e9a8..41f51877d7128 100644
--- a/llvm/lib/Support/TextEncoding.cpp
+++ b/llvm/lib/Support/TextEncoding.cpp
@@ -54,9 +54,9 @@ static std::optional<TextEncoding> getKnownEncoding(StringRef Name) {
   return std::nullopt;
 }
 
-LLVM_ATTRIBUTE_UNUSED static void
-HandleOverflow(size_t &Capacity, char *&Output, size_t &OutputLength,
-               SmallVectorImpl<char> &Result) {
+[[maybe_unused]] static void HandleOverflow(size_t &Capacity, char *&Output,
+                                            size_t &OutputLength,
+                                            SmallVectorImpl<char> &Result) {
   // No space left in output buffer. Double the size of the underlying
   // memory in the SmallVectorImpl, adjust pointer and length and continue
   // the conversion.
diff --git a/llvm/lib/Support/UnicodeNameToCodepoint.cpp b/llvm/lib/Support/UnicodeNameToCodepoint.cpp
index 8d66348cfaba6..6f8e0915ab632 100644
--- a/llvm/lib/Support/UnicodeNameToCodepoint.cpp
+++ b/llvm/lib/Support/UnicodeNameToCodepoint.cpp
@@ -476,7 +476,7 @@ nearestMatchesForCodepointName(StringRef Pattern, std::size_t MaxMatchesCount) {
       std::min(NormalizedName.size(), UnicodeNameToCodepointLargestNameSize) +
       1;
 
-  LLVM_ATTRIBUTE_UNUSED static std::size_t Rows =
+  [[maybe_unused]] static std::size_t Rows =
       UnicodeNameToCodepointLargestNameSize + 1;
 
   std::vector<char> Distances(
diff --git a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
index 80e985d823746..a2841c114a698 100644
--- a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
+++ b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
@@ -18168,7 +18168,7 @@ Align SITargetLowering::getPrefLoopAlignment(MachineLoop *ML) const {
   return CacheLineAlign;
 }
 
-LLVM_ATTRIBUTE_UNUSED
+[[maybe_unused]]
 static bool isCopyFromRegOfInlineAsm(const SDNode *N) {
   assert(N->getOpcode() == ISD::CopyFromReg);
   do {
diff --git a/llvm/lib/Target/CSKY/Disassembler/CSKYDisassembler.cpp b/llvm/lib/Target/CSKY/Disassembler/CSKYDisassembler.cpp
index 39e651d52e4d3..8945ec3446d61 100644
--- a/llvm/lib/Target/CSKY/Disassembler/CSKYDisassembler.cpp
+++ b/llvm/lib/Target/CSKY/Disassembler/CSKYDisassembler.cpp
@@ -166,7 +166,7 @@ static DecodeStatus DecodeFPR64RegisterClass(MCInst &Inst, uint64_t RegNo,
 }
 
 // TODO
-LLVM_ATTRIBUTE_UNUSED
+[[maybe_unused]]
 static DecodeStatus DecodesFPR128RegisterClass(MCInst &Inst, uint64_t RegNo,
                                                uint64_t Address,
                                                const MCDisassembler *Decoder) {
diff --git a/llvm/lib/Target/Hexagon/Disassembler/HexagonDisassembler.cpp b/llvm/lib/Target/Hexagon/Disassembler/HexagonDisassembler.cpp
index 974f6533411e0..5f180d6448d06 100644
--- a/llvm/lib/Target/Hexagon/Disassembler/HexagonDisassembler.cpp
+++ b/llvm/lib/Target/Hexagon/Disassembler/HexagonDisassembler.cpp
@@ -667,11 +667,10 @@ static DecodeStatus DecodeHvxWRRegisterClass(MCInst &Inst, unsigned RegNo,
   return DecodeRegisterClass(Inst, RegNo, HvxWRDecoderTable);
 }
 
-LLVM_ATTRIBUTE_UNUSED // Suppress warning temporarily.
-    static DecodeStatus
-    DecodeHvxVQRRegisterClass(MCInst &Inst, unsigned RegNo,
-                              uint64_t /*Address*/,
-                              const MCDisassembler *Decoder) {
+[[maybe_unused]] // Suppress warning temporarily.
+static DecodeStatus DecodeHvxVQRRegisterClass(MCInst &Inst, unsigned RegNo,
+                                              uint64_t /*Address*/,
+                                              const MCDisassembler *Decoder) {
   static const MCPhysReg HvxVQRDecoderTable[] = {
       Hexagon::VQ0,  Hexagon::VQ1,  Hexagon::VQ2,  Hexagon::VQ3,
       Hexagon::VQ4,  Hexagon::VQ5,  Hexagon::VQ6,  Hexagon::VQ7};
diff --git a/llvm/lib/Target/Hexagon/HexagonConstExtenders.cpp b/llvm/lib/Target/Hexagon/HexagonConstExtenders.cpp
index 5dde47ab3de57..a3296e0796412 100644
--- a/llvm/lib/Target/Hexagon/HexagonConstExtenders.cpp
+++ b/llvm/lib/Target/Hexagon/HexagonConstExtenders.cpp
@@ -419,8 +419,8 @@ namespace {
 
   using HCE = HexagonConstExtenders;
 
-  LLVM_ATTRIBUTE_UNUSED
-  raw_ostream &operator<< (raw_ostream &OS, const OffsetRange &OR) {
+  [[maybe_unused]]
+  raw_ostream &operator<<(raw_ostream &OS, const OffsetRange &OR) {
     if (OR.Min > OR.Max)
       OS << '!';
     OS << '[' << OR.Min << ',' << OR.Max << "]a" << unsigned(OR.Align)
@@ -435,8 +435,8 @@ namespace {
     const HexagonRegisterInfo &HRI;
   };
 
-  LLVM_ATTRIBUTE_UNUSED
-  raw_ostream &operator<< (raw_ostream &OS, const PrintRegister &P) {
+  [[maybe_unused]]
+  raw_ostream &operator<<(raw_ostream &OS, const PrintRegister &P) {
     if (P.Rs.Reg != 0)
       OS << printReg(P.Rs.Reg, &P.HRI, P.Rs.Sub);
     else
@@ -451,8 +451,8 @@ namespace {
     const HexagonRegisterInfo &HRI;
   };
 
-  LLVM_ATTRIBUTE_UNUSED
-  raw_ostream &operator<< (raw_ostream &OS, const PrintExpr &P) {
+  [[maybe_unused]]
+  raw_ostream &operator<<(raw_ostream &OS, const PrintExpr &P) {
     OS << "## " << (P.Ex.Neg ? "- " : "+ ");
     if (P.Ex.Rs.Reg != 0)
       OS << printReg(P.Ex.Rs.Reg, &P.HRI, P.Ex.Rs.Sub);
@@ -469,15 +469,15 @@ namespace {
     const HexagonRegisterInfo &HRI;
   };
 
-  LLVM_ATTRIBUTE_UNUSED
-  raw_ostream &operator<< (raw_ostream &OS, const PrintInit &P) {
+  [[maybe_unused]]
+  raw_ostream &operator<<(raw_ostream &OS, const PrintInit &P) {
     OS << '[' << P.ExtI.first << ", "
        << PrintExpr(P.ExtI.second, P.HRI) << ']';
     return OS;
   }
 
-  LLVM_ATTRIBUTE_UNUSED
-  raw_ostream &operator<< (raw_ostream &OS, const HCE::ExtDesc &ED) {
+  [[maybe_unused]]
+  raw_ostream &operator<<(raw_ostream &OS, const HCE::ExtDesc &ED) {
     assert(ED.OpNum != -1u);
     const MachineBasicBlock &MBB = *ED.getOp().getParent()->getParent();
     const MachineFunction &MF = *MBB.getParent();
@@ -493,8 +493,8 @@ namespace {
     return OS;
   }
 
-  LLVM_ATTRIBUTE_UNUSED
-  raw_ostream &operator<< (raw_ostream &OS, const HCE::ExtRoot &ER) {
+  [[maybe_unused]]
+  raw_ostream &operator<<(raw_ostream &OS, const HCE::ExtRoot &ER) {
     switch (ER.Kind) {
       case MachineOperand::MO_Immediate:
         OS << "imm:" << ER.V.ImmVal;
@@ -527,8 +527,8 @@ namespace {
     return OS;
   }
 
-  LLVM_ATTRIBUTE_UNUSED
-  raw_ostream &operator<< (raw_ostream &OS, const HCE::ExtValue &EV) {
+  [[maybe_unused]]
+  raw_ostream &operator<<(raw_ostream &OS, const HCE::ExtValue &EV) {
     OS << HCE::ExtRoot(EV) << "  off:" << EV.Offset;
     return OS;
   }
@@ -540,8 +540,8 @@ namespace {
     const HexagonRegisterInfo &HRI;
   };
 
-  LLVM_ATTRIBUTE_UNUSED
-  raw_ostream &operator<< (raw_ostream &OS, const PrintIMap &P) {
+  [[maybe_unused]]
+  raw_ostream &operator<<(raw_ostream &OS, const PrintIMap &P) {
     OS << "{\n";
     for (const std::pair<const HCE::ExtenderInit, HCE::IndexList> &Q : P.IMap) {
       OS << "  " << PrintInit(Q.first, P.HRI) << " -> {";
diff --git a/llvm/lib/Target/Hexagon/HexagonISelDAGToDAGHVX.cpp b/llvm/lib/Target/Hexagon/HexagonISelDAGToDAGHVX.cpp
index 4d96cfadc79ff..c7a4f6803a243 100644
--- a/llvm/lib/Target/Hexagon/HexagonISelDAGToDAGHVX.cpp
+++ b/llvm/lib/Target/Hexagon/HexagonISelDAGToDAGHVX.cpp
@@ -789,7 +789,7 @@ struct ShuffleMask {
   }
 };
 
-LLVM_ATTRIBUTE_UNUSED
+[[maybe_unused]]
 raw_ostream &operator<<(raw_ostream &OS, const ShuffleMask &SM) {
   SM.print(OS);
   return OS;
diff --git a/llvm/lib/Target/Hexagon/HexagonVectorCombine.cpp b/llvm/lib/Target/Hexagon/HexagonVectorCombine.cpp
index 87d052b9bb679..e4c0a16c93826 100644
--- a/llvm/lib/Target/Hexagon/HexagonVectorCombine.cpp
+++ b/llvm/lib/Target/Hexagon/HexagonVectorCombine.cpp
@@ -364,7 +364,7 @@ class AlignVectors {
   const HexagonVectorCombine &HVC;
 };
 
-LLVM_ATTRIBUTE_UNUSED
+[[maybe_unused]]
 raw_ostream &operator<<(raw_ostream &OS, const AlignVectors::AddrInfo &AI) {
   OS << "Inst: " << AI.Inst << "  " << *AI.Inst << '\n';
   OS << "Addr: " << *AI.Addr << '\n';
@@ -375,7 +375,7 @@ raw_ostream &operator<<(raw_ostream &OS, const AlignVectors::AddrInfo &AI) {
   return OS;
 }
 
-LLVM_ATTRIBUTE_UNUSED
+[[maybe_unused]]
 raw_ostream &operator<<(raw_ostream &OS, const AlignVectors::MoveGroup &MG) {
   OS << "IsLoad:" << (MG.IsLoad ? "yes" : "no");
   OS << ", IsHvx:" << (MG.IsHvx ? "yes" : "no") << '\n';
@@ -394,7 +394,7 @@ raw_ostream &operator<<(raw_ostream &OS, const AlignVectors::MoveGroup &MG) {
   return OS;
 }
 
-LLVM_ATTRIBUTE_UNUSED
+[[maybe_unused]]
 raw_ostream &operator<<(raw_ostream &OS,
                         const AlignVectors::ByteSpan::Block &B) {
   OS << "  @" << B.Pos << " [" << B.Seg.Start << ',' << B.Seg.Size << "] ";
@@ -408,7 +408,7 @@ raw_ostream &operator<<(raw_ostream &OS,
   return OS;
 }
 
-LLVM_ATTRIBUTE_UNUSED
+[[maybe_unused]]
 raw_ostream &operator<<(raw_ostream &OS, const AlignVectors::ByteSpan &BS) {
   OS << "ByteSpan[size=" << BS.size() << ", extent=" << BS.extent() << '\n';
   for (const AlignVectors::ByteSpan::Block &B : BS)
diff --git a/llvm/lib/Target/Hexagon/HexagonVectorLoopCarriedReuse.cpp b/llvm/lib/Target/Hexagon/HexagonVectorLoopCarriedReuse.cpp
index fa8ae60e3f57b..2ff5843b19429 100644
--- a/llvm/lib/Target/Hexagon/HexagonVectorLoopCarriedReuse.cpp
+++ b/llvm/lib/Target/Hexagon/HexagonVectorLoopCarriedReuse.cpp
@@ -111,7 +111,7 @@ namespace {
    friend raw_ostream &operator<< (raw_ostream &OS, const DepChain &D);
   };
 
-  LLVM_ATTRIBUTE_UNUSED
+  [[maybe_unused]]
   raw_ostream &operator<<(raw_ostream &OS, const DepChain &D) {
     const ChainOfDependences &CD = D.Chain;
     int ChainSize = CD.size();
@@ -144,7 +144,7 @@ namespace {
     bool isDefined() { return Inst2Replace != nullptr; }
   };
 
-  LLVM_ATTRIBUTE_UNUSED
+  [[maybe_unused]]
   raw_ostream &operator<<(raw_ostream &OS, const ReuseValue &RU) {
     OS << "** ReuseValue ***\n";
     OS << "Instruction to Replace: " << *(RU.Inst2Replace) << "\n";
diff --git a/llvm/lib/Target/Hexagon/MCTargetDesc/HexagonBaseInfo.h b/llvm/lib/Target/Hexagon/MCTargetDesc/HexagonBaseInfo.h
index ca982696b0600..e3094b4438e5f 100644
--- a/llvm/lib/Target/Hexagon/MCTargetDesc/HexagonBaseInfo.h
+++ b/llvm/lib/Target/Hexagon/MCTargetDesc/HexagonBaseInfo.h
@@ -275,7 +275,7 @@ namespace HexagonII {
     INST_ICLASS_ALU32_3   = 0xf0000000
   };
 
-  LLVM_ATTRIBUTE_UNUSED
+  [[maybe_unused]]
   static unsigned getMemAccessSizeInBytes(MemAccessSize S) {
     switch (S) {
       case ByteAccess:        return 1;
diff --git a/llvm/lib/Target/RISCV/RISCVVLOptimizer.cpp b/llvm/lib/Target/RISCV/RISCVVLOptimizer.cpp
index 96ad5c680e383..0a8838cbd45c7 100644
--- a/llvm/lib/Target/RISCV/RISCVVLOptimizer.cpp
+++ b/llvm/lib/Target/RISCV/RISCVVLOptimizer.cpp
@@ -156,13 +156,13 @@ FunctionPass *llvm::createRISCVVLOptimizerPass() {
   return new RISCVVLOptimizer();
 }
 
-LLVM_ATTRIBUTE_UNUSED
+[[maybe_unused]]
 static raw_ostream &operator<<(raw_ostream &OS, const OperandInfo &OI) {
   OI.print(OS);
   return OS;
 }
 
-LLVM_ATTRIBUTE_UNUSED
+[[maybe_unused]]
 static raw_ostream &operator<<(raw_ostream &OS,
                                const std::optional<OperandInfo> &OI) {
   if (OI)
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index eea84a2841764..cfeb608119416 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -3787,7 +3787,7 @@ static bool isUndefOrZeroOrInRange(ArrayRef<int> Mask, int Low, int Hi) {
 
 /// Return true if every element in Mask, is an in-place blend/select mask or is
 /// undef.
-LLVM_ATTRIBUTE_UNUSED static bool isBlendOrUndef(ArrayRef<int> Mask) {
+[[maybe_unused]] static bool isBlendOrUndef(ArrayRef<int> Mask) {
   unsigned NumElts = Mask.size();
   for (auto [I, M] : enumerate(Mask))
     if (!isUndefOrEqual(M, I) && !isUndefOrEqual(M, I + NumElts))
@@ -8096,7 +8096,7 @@ static SDValue LowerBUILD_VECTORvXi1(SDValue Op, const SDLoc &dl,
   return DstVec;
 }
 
-LLVM_ATTRIBUTE_UNUSED static bool isHorizOp(unsigned Opcode) {
+[[maybe_unused]] static bool isHorizOp(unsigned Opcode) {
   switch (Opcode) {
   case X86ISD::PACKSS:
   case X86ISD::PACKUS:
@@ -20813,7 +20813,7 @@ SDValue X86TargetLowering::FP_TO_INTHelper(SDValue Op, SelectionDAG &DAG,
     // for DAG type consistency we have to match the FP operand type.
 
     APFloat Thresh(APFloat::IEEEsingle(), APInt(32, 0x5f000000));
-    LLVM_ATTRIBUTE_UNUSED APFloat::opStatus Status = APFloat::opOK;
+    [[maybe_unused]] APFloat::opStatus Status = APFloat::opOK;
     bool LosesInfo = false;
     if (TheVT == MVT::f64)
       // The rounding mode is irrelevant as the conversion should be exact.
diff --git a/llvm/unittests/ADT/TypeTraitsTest.cpp b/llvm/unittests/ADT/TypeTraitsTest.cpp
index a56aa7e98cfe0..f9b8d6d2573d4 100644
--- a/llvm/unittests/ADT/TypeTraitsTest.cpp
+++ b/llvm/unittests/ADT/TypeTraitsTest.cpp
@@ -40,9 +40,7 @@ struct Foo {
 struct CheckMethodPointer : CheckFunctionTraits<decltype(&Foo::func)> {};
 
 /// Test lambda references.
-LLVM_ATTRIBUTE_UNUSED auto lambdaFunc = [](const int &v) -> bool {
-  return true;
-};
+[[maybe_unused]] auto lambdaFunc = [](const int &v) -> bool { return true; };
 struct CheckLambda : CheckFunctionTraits<decltype(lambdaFunc)> {};
 
 } // end anonymous namespace