diff --git a/llvm/lib/IR/Attributes.cpp b/llvm/lib/IR/Attributes.cpp
index a9c4b9f6df649f..1a90b945eb2bfe 100644
--- a/llvm/lib/IR/Attributes.cpp
+++ b/llvm/lib/IR/Attributes.cpp
@@ -600,8 +600,7 @@ enum AttributeProperty {
 static bool hasAttributeProperty(Attribute::AttrKind Kind,
                                  AttributeProperty Prop) {
   unsigned Index = Kind - 1;
-  assert(Index < sizeof(AttrPropTable) / sizeof(AttrPropTable[0]) &&
-         "Invalid attribute kind");
+  assert(Index < std::size(AttrPropTable) && "Invalid attribute kind");
   return AttrPropTable[Index] & Prop;
 }
 
diff --git a/llvm/lib/IR/ModuleSummaryIndex.cpp b/llvm/lib/IR/ModuleSummaryIndex.cpp
index 3e82987801c7f1..2d1440756a95cf 100644
--- a/llvm/lib/IR/ModuleSummaryIndex.cpp
+++ b/llvm/lib/IR/ModuleSummaryIndex.cpp
@@ -570,8 +570,7 @@ void ModuleSummaryIndex::exportToDot(
         " [color=brown]; // call (hotness : Hot)",
         " [style=bold,color=red]; // call (hotness : Critical)"};
 
-    assert(static_cast<size_t>(TypeOrHotness) <
-           sizeof(EdgeAttrs) / sizeof(EdgeAttrs[0]));
+    assert(static_cast<size_t>(TypeOrHotness) < std::size(EdgeAttrs));
     OS << Pfx << NodeId(SrcMod, SrcId) << " -> " << NodeId(DstMod, DstId)
        << EdgeAttrs[TypeOrHotness] << "\n";
   };
diff --git a/llvm/lib/ProfileData/InstrProfWriter.cpp b/llvm/lib/ProfileData/InstrProfWriter.cpp
index de632695ca499f..bbea275ab445e6 100644
--- a/llvm/lib/ProfileData/InstrProfWriter.cpp
+++ b/llvm/lib/ProfileData/InstrProfWriter.cpp
@@ -490,7 +490,7 @@ Error InstrProfWriter::writeImpl(ProfOStream &OS) {
       {CSSummaryOffset, reinterpret_cast<uint64_t *>(TheCSSummary.get()),
        (int)CSSummarySize}};
 
-  OS.patch(PatchItems, sizeof(PatchItems) / sizeof(*PatchItems));
+  OS.patch(PatchItems, std::size(PatchItems));
 
   for (const auto &I : FunctionData)
     for (const auto &F : I.getValue())
diff --git a/llvm/lib/Target/AMDGPU/AMDGPUPropagateAttributes.cpp b/llvm/lib/Target/AMDGPU/AMDGPUPropagateAttributes.cpp
index dafbeaeaec528f..b0099ffd18a124 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUPropagateAttributes.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPUPropagateAttributes.cpp
@@ -57,8 +57,7 @@ static constexpr const FeatureBitset TargetFeatures = {
 // TODO: Support conservative min/max merging instead of cloning.
 static constexpr const char *AttributeNames[] = {"amdgpu-waves-per-eu"};
 
-static constexpr unsigned NumAttr =
-  sizeof(AttributeNames) / sizeof(AttributeNames[0]);
+static constexpr unsigned NumAttr = std::size(AttributeNames);
 
 class AMDGPUPropagateAttributes {
 
diff --git a/llvm/lib/Target/Hexagon/Disassembler/HexagonDisassembler.cpp b/llvm/lib/Target/Hexagon/Disassembler/HexagonDisassembler.cpp
index 8792ce354c061c..de6ca0aa9cbb40 100644
--- a/llvm/lib/Target/Hexagon/Disassembler/HexagonDisassembler.cpp
+++ b/llvm/lib/Target/Hexagon/Disassembler/HexagonDisassembler.cpp
@@ -807,7 +807,7 @@ static const uint16_t SysRegDecoderTable[] = {
 static DecodeStatus DecodeSysRegsRegisterClass(MCInst &Inst, unsigned RegNo,
                                                uint64_t /*Address*/,
                                                const MCDisassembler *Decoder) {
-  if (RegNo >= sizeof(SysRegDecoderTable) / sizeof(SysRegDecoderTable[0]))
+  if (RegNo >= std::size(SysRegDecoderTable))
     return MCDisassembler::Fail;
 
   if (SysRegDecoderTable[RegNo] == Hexagon::NoRegister)
@@ -835,7 +835,7 @@ static DecodeStatus
 DecodeSysRegs64RegisterClass(MCInst &Inst, unsigned RegNo, uint64_t /*Address*/,
                              const MCDisassembler *Decoder) {
   RegNo = RegNo >> 1;
-  if (RegNo >= sizeof(SysReg64DecoderTable) / sizeof(SysReg64DecoderTable[0]))
+  if (RegNo >= std::size(SysReg64DecoderTable))
     return MCDisassembler::Fail;
 
   if (SysReg64DecoderTable[RegNo] == Hexagon::NoRegister)
diff --git a/llvm/lib/Target/Lanai/LanaiISelLowering.cpp b/llvm/lib/Target/Lanai/LanaiISelLowering.cpp
index b80c68e251e4b3..d5639bd9a329cc 100644
--- a/llvm/lib/Target/Lanai/LanaiISelLowering.cpp
+++ b/llvm/lib/Target/Lanai/LanaiISelLowering.cpp
@@ -951,8 +951,7 @@ SDValue LanaiTargetLowering::LowerMUL(SDValue Op, SelectionDAG &DAG) const {
 
   // Assemble multiplication from shift, add, sub using NAF form and running
   // sum.
-  for (unsigned int I = 0; I < sizeof(SignedDigit) / sizeof(SignedDigit[0]);
-       ++I) {
+  for (unsigned int I = 0; I < std::size(SignedDigit); ++I) {
     if (SignedDigit[I] == 0)
       continue;
 
diff --git a/llvm/lib/Target/PowerPC/PPCCallingConv.cpp b/llvm/lib/Target/PowerPC/PPCCallingConv.cpp
index cd67a09ae9358f..ff792fda8fb2d5 100644
--- a/llvm/lib/Target/PowerPC/PPCCallingConv.cpp
+++ b/llvm/lib/Target/PowerPC/PPCCallingConv.cpp
@@ -120,7 +120,7 @@ static bool CC_PPC32_SPE_CustomSplitFP64(unsigned &ValNo, MVT &ValVT,
     return false;
 
   unsigned i;
-  for (i = 0; i < sizeof(HiRegList) / sizeof(HiRegList[0]); ++i)
+  for (i = 0; i < std::size(HiRegList); ++i)
     if (HiRegList[i] == Reg)
       break;
 
@@ -149,7 +149,7 @@ static bool CC_PPC32_SPE_RetF64(unsigned &ValNo, MVT &ValVT,
     return false;
 
   unsigned i;
-  for (i = 0; i < sizeof(HiRegList) / sizeof(HiRegList[0]); ++i)
+  for (i = 0; i < std::size(HiRegList); ++i)
     if (HiRegList[i] == Reg)
       break;
 
diff --git a/llvm/lib/Target/Sparc/MCTargetDesc/SparcInstPrinter.cpp b/llvm/lib/Target/Sparc/MCTargetDesc/SparcInstPrinter.cpp
index 8e46219460080f..cc65b95a00d4f1 100644
--- a/llvm/lib/Target/Sparc/MCTargetDesc/SparcInstPrinter.cpp
+++ b/llvm/lib/Target/Sparc/MCTargetDesc/SparcInstPrinter.cpp
@@ -222,7 +222,7 @@ void SparcInstPrinter::printMembarTag(const MCInst *MI, int opNum,
   }
 
   bool First = true;
-  for (unsigned i = 0; i < sizeof(TagNames) / sizeof(char *); i++) {
+  for (unsigned i = 0; i < std::size(TagNames); i++) {
     if (Imm & (1 << i)) {
       O << (First ? "" : " | ") << TagNames[i];
       First = false;
diff --git a/llvm/lib/Target/X86/X86CallingConv.cpp b/llvm/lib/Target/X86/X86CallingConv.cpp
index ded93fdc011cfa..ad61334643f852 100644
--- a/llvm/lib/Target/X86/X86CallingConv.cpp
+++ b/llvm/lib/Target/X86/X86CallingConv.cpp
@@ -240,7 +240,7 @@ static bool CC_X86_32_MCUInReg(unsigned &ValNo, MVT &ValVT, MVT &LocVT,
   // This is similar to CCAssignToReg<[EAX, EDX, ECX]>, but makes sure
   // not to split i64 and double between a register and stack
   static const MCPhysReg RegList[] = {X86::EAX, X86::EDX, X86::ECX};
-  static const unsigned NumRegs = sizeof(RegList) / sizeof(RegList[0]);
+  static const unsigned NumRegs = std::size(RegList);
 
   SmallVectorImpl<CCValAssign> &PendingMembers = State.getPendingLocs();
 
diff --git a/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
index 76f7136c3d7e4e..2c0fb3584dec48 100644
--- a/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
@@ -1031,7 +1031,7 @@ unsigned HWAddressSanitizer::retagMask(unsigned AllocaNo) {
                                  48, 16,  120, 248, 56,  24,  8,   124, 252,
                                  60, 28,  12,  4,   126, 254, 62,  30,  14,
                                  6,  2,   127, 63,  31,  15,  7,   3,   1};
-  return FastMasks[AllocaNo % (sizeof(FastMasks) / sizeof(FastMasks[0]))];
+  return FastMasks[AllocaNo % std::size(FastMasks)];
 }
 
 Value *HWAddressSanitizer::applyTagMask(IRBuilder<> &IRB, Value *OldTag) {
diff --git a/llvm/lib/XRay/InstrumentationMap.cpp b/llvm/lib/XRay/InstrumentationMap.cpp
index c60efa465bb696..a68ca198e5573a 100644
--- a/llvm/lib/XRay/InstrumentationMap.cpp
+++ b/llvm/lib/XRay/InstrumentationMap.cpp
@@ -188,7 +188,7 @@ loadObj(StringRef Filename, object::OwningBinary<object::ObjectFile> &ObjFile,
         SledEntry::FunctionKinds::TAIL,
         SledEntry::FunctionKinds::LOG_ARGS_ENTER,
         SledEntry::FunctionKinds::CUSTOM_EVENT};
-    if (Kind >= sizeof(Kinds) / sizeof(Kinds[0]))
+    if (Kind >= std::size(Kinds))
       return errorCodeToError(
           std::make_error_code(std::errc::executable_format_error));
     Entry.Kind = Kinds[Kind];
diff --git a/llvm/tools/llvm-exegesis/lib/X86/Target.cpp b/llvm/tools/llvm-exegesis/lib/X86/Target.cpp
index 2f8275978455f9..6ecb6b17f20711 100644
--- a/llvm/tools/llvm-exegesis/lib/X86/Target.cpp
+++ b/llvm/tools/llvm-exegesis/lib/X86/Target.cpp
@@ -709,8 +709,7 @@ class ExegesisX86Target : public ExegesisTarget {
 
   ArrayRef<unsigned> getUnavailableRegisters() const override {
     return makeArrayRef(kUnavailableRegisters,
-                        sizeof(kUnavailableRegisters) /
-                            sizeof(kUnavailableRegisters[0]));
+                        std::size(kUnavailableRegisters));
   }
 
   bool allowAsBackToBack(const Instruction &Instr) const override {
diff --git a/llvm/tools/llvm-readobj/COFFDumper.cpp b/llvm/tools/llvm-readobj/COFFDumper.cpp
index fdfb5de658dd49..19c9830c056257 100644
--- a/llvm/tools/llvm-readobj/COFFDumper.cpp
+++ b/llvm/tools/llvm-readobj/COFFDumper.cpp
@@ -756,7 +756,7 @@ void COFFDumper::printPEHeader(const PEHeader *Hdr) {
     };
 
     for (uint32_t i = 0; i < Hdr->NumberOfRvaAndSize; ++i)
-      if (i < sizeof(directory) / sizeof(char *))
+      if (i < std::size(directory))
         printDataDirectory(i, directory[i]);
       else
         printDataDirectory(i, "Unknown");
diff --git a/llvm/unittests/ADT/SimpleIListTest.cpp b/llvm/unittests/ADT/SimpleIListTest.cpp
index 17dd140c0a4da1..c2992baf8a5f7d 100644
--- a/llvm/unittests/ADT/SimpleIListTest.cpp
+++ b/llvm/unittests/ADT/SimpleIListTest.cpp
@@ -634,7 +634,7 @@ TEST(SimpleIListTest, TaggedLists) {
     L2.push_back(Ns[I]);
 
   // Check that each list is correct.
-  EXPECT_EQ(sizeof(Order1) / sizeof(int), L1.size());
+  EXPECT_EQ(std::size(Order1), L1.size());
   auto I1 = L1.begin();
   for (int I : Order1) {
     EXPECT_EQ(Ns[I].getIterator1(), I1);
@@ -642,7 +642,7 @@ TEST(SimpleIListTest, TaggedLists) {
   }
   EXPECT_EQ(L1.end(), I1);
 
-  EXPECT_EQ(sizeof(Order2) / sizeof(int), L2.size());
+  EXPECT_EQ(std::size(Order2), L2.size());
   auto I2 = L2.begin();
   for (int I : Order2) {
     EXPECT_EQ(Ns[I].getIterator2(), I2);
diff --git a/llvm/unittests/BinaryFormat/TestFileMagic.cpp b/llvm/unittests/BinaryFormat/TestFileMagic.cpp
index 235e4bb05f0943..b09a2c07309f82 100644
--- a/llvm/unittests/BinaryFormat/TestFileMagic.cpp
+++ b/llvm/unittests/BinaryFormat/TestFileMagic.cpp
@@ -128,7 +128,7 @@ TEST_F(MagicTest, Magic) {
   };
 
   // Create some files filled with magic.
-  for (type *i = types, *e = types + (sizeof(types) / sizeof(type)); i != e;
+  for (type *i = types, *e = types + std::size(types); i != e;
        ++i) {
     SmallString<128> file_pathname(TestDirectory);
     llvm::sys::path::append(file_pathname, i->filename);
diff --git a/llvm/unittests/ProfileData/InstrProfTest.cpp b/llvm/unittests/ProfileData/InstrProfTest.cpp
index aa71afeaf2c6fa..cbc04d2919c8bb 100644
--- a/llvm/unittests/ProfileData/InstrProfTest.cpp
+++ b/llvm/unittests/ProfileData/InstrProfTest.cpp
@@ -1112,7 +1112,7 @@ TEST_P(MaybeSparseInstrProfTest, instr_prof_symtab_module_test) {
   StringRef Funcs[] = {"Gfoo", "Gblah", "Gbar", "Ifoo", "Iblah", "Ibar",
                        "Pfoo", "Pblah", "Pbar", "Wfoo", "Wblah", "Wbar"};
 
-  for (unsigned I = 0; I < sizeof(Funcs) / sizeof(*Funcs); I++) {
+  for (unsigned I = 0; I < std::size(Funcs); I++) {
     Function *F = M->getFunction(Funcs[I]);
     ASSERT_TRUE(F != nullptr);
     std::string PGOName = getPGOFuncName(*F);
diff --git a/llvm/unittests/Support/CommandLineTest.cpp b/llvm/unittests/Support/CommandLineTest.cpp
index df33e5309945aa..0d0b6ec471ebc4 100644
--- a/llvm/unittests/Support/CommandLineTest.cpp
+++ b/llvm/unittests/Support/CommandLineTest.cpp
@@ -740,7 +740,7 @@ TEST(CommandLineTest, DefaultOptions) {
   StackOption<std::string> SC2_Foo("foo", cl::sub(SC2));
 
   const char *args0[] = {"prog", "-b", "args0 bar string", "-f"};
-  EXPECT_TRUE(cl::ParseCommandLineOptions(sizeof(args0) / sizeof(char *), args0,
+  EXPECT_TRUE(cl::ParseCommandLineOptions(std::size(args0), args0,
                                           StringRef(), &llvm::nulls()));
   EXPECT_EQ(Bar, "args0 bar string");
   EXPECT_TRUE(Foo);
@@ -750,7 +750,7 @@ TEST(CommandLineTest, DefaultOptions) {
   cl::ResetAllOptionOccurrences();
 
   const char *args1[] = {"prog", "sc1", "-b", "-bar", "args1 bar string", "-f"};
-  EXPECT_TRUE(cl::ParseCommandLineOptions(sizeof(args1) / sizeof(char *), args1,
+  EXPECT_TRUE(cl::ParseCommandLineOptions(std::size(args1), args1,
                                           StringRef(), &llvm::nulls()));
   EXPECT_EQ(Bar, "args1 bar string");
   EXPECT_TRUE(Foo);
@@ -766,7 +766,7 @@ TEST(CommandLineTest, DefaultOptions) {
 
   const char *args2[] = {"prog", "sc2", "-b", "args2 bar string",
                          "-f", "-foo", "foo string"};
-  EXPECT_TRUE(cl::ParseCommandLineOptions(sizeof(args2) / sizeof(char *), args2,
+  EXPECT_TRUE(cl::ParseCommandLineOptions(std::size(args2), args2,
                                           StringRef(), &llvm::nulls()));
   EXPECT_EQ(Bar, "args2 bar string");
   EXPECT_TRUE(Foo);
diff --git a/llvm/unittests/TextAPI/TextStubV1Tests.cpp b/llvm/unittests/TextAPI/TextStubV1Tests.cpp
index a7995df346f8b1..e2c6cd204e1ecf 100644
--- a/llvm/unittests/TextAPI/TextStubV1Tests.cpp
+++ b/llvm/unittests/TextAPI/TextStubV1Tests.cpp
@@ -104,7 +104,7 @@ TEST(TBDv1, ReadFile) {
   }
   llvm::sort(Exports);
 
-  EXPECT_EQ(sizeof(TBDv1Symbols) / sizeof(ExportedSymbol), Exports.size());
+  EXPECT_EQ(std::size(TBDv1Symbols), Exports.size());
   EXPECT_TRUE(
       std::equal(Exports.begin(), Exports.end(), std::begin(TBDv1Symbols)));
 
diff --git a/llvm/unittests/TextAPI/TextStubV2Tests.cpp b/llvm/unittests/TextAPI/TextStubV2Tests.cpp
index a2b4b1a419f405..a4ceb3c2a8b7a4 100644
--- a/llvm/unittests/TextAPI/TextStubV2Tests.cpp
+++ b/llvm/unittests/TextAPI/TextStubV2Tests.cpp
@@ -105,7 +105,7 @@ TEST(TBDv2, ReadFile) {
   }
   llvm::sort(Exports);
 
-  EXPECT_EQ(sizeof(TBDv2Symbols) / sizeof(ExportedSymbol), Exports.size());
+  EXPECT_EQ(std::size(TBDv2Symbols), Exports.size());
   EXPECT_TRUE(
       std::equal(Exports.begin(), Exports.end(), std::begin(TBDv2Symbols)));
 }
diff --git a/llvm/unittests/TextAPI/TextStubV3Tests.cpp b/llvm/unittests/TextAPI/TextStubV3Tests.cpp
index 1a42e5440d7431..10e8ab41dd323e 100644
--- a/llvm/unittests/TextAPI/TextStubV3Tests.cpp
+++ b/llvm/unittests/TextAPI/TextStubV3Tests.cpp
@@ -113,7 +113,7 @@ TEST(TBDv3, ReadFile) {
   }
   llvm::sort(Exports);
 
-  EXPECT_EQ(sizeof(TBDv3Symbols) / sizeof(ExportedSymbol), Exports.size());
+  EXPECT_EQ(std::size(TBDv3Symbols), Exports.size());
   EXPECT_TRUE(
       std::equal(Exports.begin(), Exports.end(), std::begin(TBDv3Symbols)));
 }
@@ -205,7 +205,7 @@ TEST(TBDv3, ReadMultipleDocuments) {
   }
   llvm::sort(Exports);
 
-  EXPECT_EQ(sizeof(TBDv3Symbols) / sizeof(ExportedSymbol), Exports.size());
+  EXPECT_EQ(std::size(TBDv3Symbols), Exports.size());
   EXPECT_TRUE(
       std::equal(Exports.begin(), Exports.end(), std::begin(TBDv3Symbols)));
 
diff --git a/llvm/unittests/TextAPI/TextStubV4Tests.cpp b/llvm/unittests/TextAPI/TextStubV4Tests.cpp
index 641f95ff10f293..f2327ca85d687a 100644
--- a/llvm/unittests/TextAPI/TextStubV4Tests.cpp
+++ b/llvm/unittests/TextAPI/TextStubV4Tests.cpp
@@ -143,12 +143,9 @@ TEST(TBDv4, ReadFile) {
       {SymbolKind::GlobalSymbol, "_symD", false, false},
   };
 
-  EXPECT_EQ(sizeof(ExpectedExportedSymbols) / sizeof(ExportedSymbol),
-            Exports.size());
-  EXPECT_EQ(sizeof(ExpectedReexportedSymbols) / sizeof(ExportedSymbol),
-            Reexports.size());
-  EXPECT_EQ(sizeof(ExpectedUndefinedSymbols) / sizeof(ExportedSymbol),
-            Undefineds.size());
+  EXPECT_EQ(std::size(ExpectedExportedSymbols), Exports.size());
+  EXPECT_EQ(std::size(ExpectedReexportedSymbols), Reexports.size());
+  EXPECT_EQ(std::size(ExpectedUndefinedSymbols), Undefineds.size());
   EXPECT_TRUE(std::equal(Exports.begin(), Exports.end(),
                          std::begin(ExpectedExportedSymbols)));
   EXPECT_TRUE(std::equal(Reexports.begin(), Reexports.end(),
@@ -313,12 +310,9 @@ TEST(TBDv4, ReadMultipleDocuments) {
       {SymbolKind::GlobalSymbol, "_symD", false, false},
   };
 
-  EXPECT_EQ(sizeof(ExpectedExportedSymbols) / sizeof(ExportedSymbol),
-            Exports.size());
-  EXPECT_EQ(sizeof(ExpectedReexportedSymbols) / sizeof(ExportedSymbol),
-            Reexports.size());
-  EXPECT_EQ(sizeof(ExpectedUndefinedSymbols) / sizeof(ExportedSymbol),
-            Undefineds.size());
+  EXPECT_EQ(std::size(ExpectedExportedSymbols), Exports.size());
+  EXPECT_EQ(std::size(ExpectedReexportedSymbols), Reexports.size());
+  EXPECT_EQ(std::size(ExpectedUndefinedSymbols), Undefineds.size());
   EXPECT_TRUE(std::equal(Exports.begin(), Exports.end(),
                          std::begin(ExpectedExportedSymbols)));
   EXPECT_TRUE(std::equal(Reexports.begin(), Reexports.end(),