diff --git a/clang/include/clang/AST/OpenMPClause.h b/clang/include/clang/AST/OpenMPClause.h
--- a/clang/include/clang/AST/OpenMPClause.h
+++ b/clang/include/clang/AST/OpenMPClause.h
@@ -5785,12 +5785,11 @@
                                   /*SupportsMapper=*/true, &MapperQualifierLoc,
                                   &MapperIdInfo),
         MapType(MapType), MapTypeIsImplicit(MapTypeIsImplicit), MapLoc(MapLoc) {
-    assert(llvm::array_lengthof(MapTypeModifiers) == MapModifiers.size() &&
+    assert(std::size(MapTypeModifiers) == MapModifiers.size() &&
            "Unexpected number of map type modifiers.");
     llvm::copy(MapModifiers, std::begin(MapTypeModifiers));
 
-    assert(llvm::array_lengthof(MapTypeModifiersLoc) ==
-               MapModifiersLoc.size() &&
+    assert(std::size(MapTypeModifiersLoc) == MapModifiersLoc.size() &&
            "Unexpected number of map type modifier locations.");
     llvm::copy(MapModifiersLoc, std::begin(MapTypeModifiersLoc));
   }
@@ -6707,12 +6706,11 @@
       : OMPMappableExprListClause(llvm::omp::OMPC_to, Locs, Sizes,
                                   /*SupportsMapper=*/true, &MapperQualifierLoc,
                                   &MapperIdInfo) {
-    assert(llvm::array_lengthof(MotionModifiers) == TheMotionModifiers.size() &&
+    assert(std::size(MotionModifiers) == TheMotionModifiers.size() &&
            "Unexpected number of motion modifiers.");
     llvm::copy(TheMotionModifiers, std::begin(MotionModifiers));
 
-    assert(llvm::array_lengthof(MotionModifiersLoc) ==
-               TheMotionModifiersLoc.size() &&
+    assert(std::size(MotionModifiersLoc) == TheMotionModifiersLoc.size() &&
            "Unexpected number of motion modifier locations.");
     llvm::copy(TheMotionModifiersLoc, std::begin(MotionModifiersLoc));
   }
@@ -6909,12 +6907,11 @@
       : OMPMappableExprListClause(llvm::omp::OMPC_from, Locs, Sizes,
                                   /*SupportsMapper=*/true, &MapperQualifierLoc,
                                   &MapperIdInfo) {
-    assert(llvm::array_lengthof(MotionModifiers) == TheMotionModifiers.size() &&
+    assert(std::size(MotionModifiers) == TheMotionModifiers.size() &&
            "Unexpected number of motion modifiers.");
     llvm::copy(TheMotionModifiers, std::begin(MotionModifiers));
 
-    assert(llvm::array_lengthof(MotionModifiersLoc) ==
-               TheMotionModifiersLoc.size() &&
+    assert(std::size(MotionModifiersLoc) == TheMotionModifiersLoc.size() &&
            "Unexpected number of motion modifier locations.");
     llvm::copy(TheMotionModifiersLoc, std::begin(MotionModifiersLoc));
   }
diff --git a/clang/lib/AST/AttrDocTable.cpp b/clang/lib/AST/AttrDocTable.cpp
--- a/clang/lib/AST/AttrDocTable.cpp
+++ b/clang/lib/AST/AttrDocTable.cpp
@@ -21,7 +21,7 @@
 };
 
 llvm::StringRef clang::Attr::getDocumentation(clang::attr::Kind K) {
-  if(K < llvm::array_lengthof(AttrDoc))
+  if (K < std::size(AttrDoc))
     return AttrDoc[K];
   return "";
 }
diff --git a/clang/lib/AST/CommentCommandTraits.cpp b/clang/lib/AST/CommentCommandTraits.cpp
--- a/clang/lib/AST/CommentCommandTraits.cpp
+++ b/clang/lib/AST/CommentCommandTraits.cpp
@@ -16,8 +16,8 @@
 #include "clang/AST/CommentCommandInfo.inc"
 
 CommandTraits::CommandTraits(llvm::BumpPtrAllocator &Allocator,
-                             const CommentOptions &CommentOptions) :
-    NextID(llvm::array_lengthof(Commands)), Allocator(Allocator) {
+                             const CommentOptions &CommentOptions)
+    : NextID(std::size(Commands)), Allocator(Allocator) {
   registerCommentOptions(CommentOptions);
 }
 
@@ -115,7 +115,7 @@
 
 const CommandInfo *CommandTraits::getBuiltinCommandInfo(
                                                   unsigned CommandID) {
-  if (CommandID < llvm::array_lengthof(Commands))
+  if (CommandID < std::size(Commands))
     return &Commands[CommandID];
   return nullptr;
 }
@@ -131,7 +131,7 @@
 
 const CommandInfo *CommandTraits::getRegisteredCommandInfo(
                                                   unsigned CommandID) const {
-  return RegisteredCommands[CommandID - llvm::array_lengthof(Commands)];
+  return RegisteredCommands[CommandID - std::size(Commands)];
 }
 
 } // end namespace comments
diff --git a/clang/lib/Basic/DiagnosticIDs.cpp b/clang/lib/Basic/DiagnosticIDs.cpp
--- a/clang/lib/Basic/DiagnosticIDs.cpp
+++ b/clang/lib/Basic/DiagnosticIDs.cpp
@@ -202,7 +202,7 @@
 
 } // namespace
 
-static const unsigned StaticDiagInfoSize = llvm::array_lengthof(StaticDiagInfo);
+static const unsigned StaticDiagInfoSize = std::size(StaticDiagInfo);
 
 /// GetDiagInfo - Return the StaticDiagInfoRec entry for the specified DiagID,
 /// or null if the ID is invalid.
@@ -317,7 +317,7 @@
 
 /// getNumberOfCategories - Return the number of categories
 unsigned DiagnosticIDs::getNumberOfCategories() {
-  return llvm::array_lengthof(CategoryNameTable) - 1;
+  return std::size(CategoryNameTable) - 1;
 }
 
 /// getCategoryNameFromID - Given a category ID, return the name of the
diff --git a/clang/lib/Basic/Targets/NVPTX.h b/clang/lib/Basic/Targets/NVPTX.h
--- a/clang/lib/Basic/Targets/NVPTX.h
+++ b/clang/lib/Basic/Targets/NVPTX.h
@@ -159,7 +159,7 @@
   /// DWARF.
   Optional<unsigned>
   getDWARFAddressSpace(unsigned AddressSpace) const override {
-    if (AddressSpace >= llvm::array_lengthof(NVPTXDWARFAddrSpaceMap) ||
+    if (AddressSpace >= std::size(NVPTXDWARFAddrSpaceMap) ||
         NVPTXDWARFAddrSpaceMap[AddressSpace] < 0)
       return llvm::None;
     return NVPTXDWARFAddrSpaceMap[AddressSpace];
diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -3297,7 +3297,7 @@
   assert(IsSanitizerScope);
   assert(Checked.size() > 0);
   assert(CheckHandler >= 0 &&
-         size_t(CheckHandler) < llvm::array_lengthof(SanitizerHandlers));
+         size_t(CheckHandler) < std::size(SanitizerHandlers));
   const StringRef CheckName = SanitizerHandlers[CheckHandler].Name;
 
   llvm::Value *FatalCond = nullptr;
diff --git a/clang/lib/CodeGen/CGObjC.cpp b/clang/lib/CodeGen/CGObjC.cpp
--- a/clang/lib/CodeGen/CGObjC.cpp
+++ b/clang/lib/CodeGen/CGObjC.cpp
@@ -1749,7 +1749,7 @@
     &CGM.getContext().Idents.get("count")
   };
   Selector FastEnumSel =
-    CGM.getContext().Selectors.getSelector(llvm::array_lengthof(II), &II[0]);
+      CGM.getContext().Selectors.getSelector(std::size(II), &II[0]);
 
   QualType ItemsTy =
     getContext().getConstantArrayType(getContext().getObjCIdType(),
diff --git a/clang/lib/Driver/ToolChains/Darwin.cpp b/clang/lib/Driver/ToolChains/Darwin.cpp
--- a/clang/lib/Driver/ToolChains/Darwin.cpp
+++ b/clang/lib/Driver/ToolChains/Darwin.cpp
@@ -1809,7 +1809,7 @@
       "WATCHOS_DEPLOYMENT_TARGET",
       "DRIVERKIT_DEPLOYMENT_TARGET",
   };
-  static_assert(llvm::array_lengthof(EnvVars) == Darwin::LastDarwinPlatform + 1,
+  static_assert(std::size(EnvVars) == Darwin::LastDarwinPlatform + 1,
                 "Missing platform");
   for (const auto &I : llvm::enumerate(llvm::makeArrayRef(EnvVars))) {
     if (char *Env = ::getenv(I.value()))
@@ -1830,11 +1830,11 @@
           Targets[Darwin::TvOS] = "";
   } else {
     // Don't allow conflicts in any other platform.
-    unsigned FirstTarget = llvm::array_lengthof(Targets);
-    for (unsigned I = 0; I != llvm::array_lengthof(Targets); ++I) {
+    unsigned FirstTarget = std::size(Targets);
+    for (unsigned I = 0; I != std::size(Targets); ++I) {
       if (Targets[I].empty())
         continue;
-      if (FirstTarget == llvm::array_lengthof(Targets))
+      if (FirstTarget == std::size(Targets))
         FirstTarget = I;
       else
         TheDriver.Diag(diag::err_drv_conflicting_deployment_targets)
diff --git a/clang/lib/Driver/Types.cpp b/clang/lib/Driver/Types.cpp
--- a/clang/lib/Driver/Types.cpp
+++ b/clang/lib/Driver/Types.cpp
@@ -42,7 +42,7 @@
 #include "clang/Driver/Types.def"
 #undef TYPE
 };
-static const unsigned numTypes = llvm::array_lengthof(TypeInfos);
+static const unsigned numTypes = std::size(TypeInfos);
 
 static const TypeInfo &getInfo(unsigned id) {
   assert(id > 0 && id - 1 < numTypes && "Invalid Type ID.");
diff --git a/clang/lib/Frontend/PrintPreprocessedOutput.cpp b/clang/lib/Frontend/PrintPreprocessedOutput.cpp
--- a/clang/lib/Frontend/PrintPreprocessedOutput.cpp
+++ b/clang/lib/Frontend/PrintPreprocessedOutput.cpp
@@ -877,7 +877,7 @@
     } else if (Tok.isLiteral() && !Tok.needsCleaning() &&
                Tok.getLiteralData()) {
       OS.write(Tok.getLiteralData(), Tok.getLength());
-    } else if (Tok.getLength() < llvm::array_lengthof(Buffer)) {
+    } else if (Tok.getLength() < std::size(Buffer)) {
       const char *TokPtr = Buffer;
       unsigned Len = PP.getSpelling(Tok, TokPtr);
       OS.write(TokPtr, Len);
diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -1417,7 +1417,7 @@
   ArgsUnion Args[] = {Language.get(), DefinedInExpr.get(),
                       GeneratedDeclaration};
   Attrs.addNew(&ExternalSourceSymbol, SourceRange(Loc, T.getCloseLocation()),
-               ScopeName, ScopeLoc, Args, llvm::array_lengthof(Args), Syntax);
+               ScopeName, ScopeLoc, Args, std::size(Args), Syntax);
 }
 
 /// Parse the contents of the "objc_bridge_related" attribute.
@@ -1538,7 +1538,7 @@
 
   ArgsUnion Args[] = {SwiftType};
   Attrs.addNew(&AttrName, SourceRange(AttrNameLoc, T.getCloseLocation()),
-               ScopeName, ScopeLoc, Args, llvm::array_lengthof(Args), Syntax);
+               ScopeName, ScopeLoc, Args, std::size(Args), Syntax);
 }
 
 void Parser::ParseTypeTagForDatatypeAttribute(IdentifierInfo &AttrName,
diff --git a/clang/lib/Sema/DeclSpec.cpp b/clang/lib/Sema/DeclSpec.cpp
--- a/clang/lib/Sema/DeclSpec.cpp
+++ b/clang/lib/Sema/DeclSpec.cpp
@@ -239,7 +239,7 @@
     // is already used (consider a function returning a function pointer) or too
     // small (function with too many parameters), go to the heap.
     if (!TheDeclarator.InlineStorageUsed &&
-        NumParams <= llvm::array_lengthof(TheDeclarator.InlineParams)) {
+        NumParams <= std::size(TheDeclarator.InlineParams)) {
       I.Fun.Params = TheDeclarator.InlineParams;
       new (I.Fun.Params) ParamInfo[NumParams];
       I.Fun.DeleteParams = false;
@@ -308,8 +308,7 @@
 
   // Allocate storage for bindings and stash them away.
   if (Bindings.size()) {
-    if (!InlineStorageUsed &&
-        Bindings.size() <= llvm::array_lengthof(InlineBindings)) {
+    if (!InlineStorageUsed && Bindings.size() <= std::size(InlineBindings)) {
       BindingGroup.Bindings = InlineBindings;
       BindingGroup.DeleteBindings = false;
       InlineStorageUsed = true;
diff --git a/clang/lib/Sema/ParsedAttr.cpp b/clang/lib/Sema/ParsedAttr.cpp
--- a/clang/lib/Sema/ParsedAttr.cpp
+++ b/clang/lib/Sema/ParsedAttr.cpp
@@ -111,7 +111,7 @@
 
 const ParsedAttrInfo &ParsedAttrInfo::get(const AttributeCommonInfo &A) {
   // If we have a ParsedAttrInfo for this ParsedAttr then return that.
-  if ((size_t)A.getParsedKind() < llvm::array_lengthof(AttrInfoMap))
+  if ((size_t)A.getParsedKind() < std::size(AttrInfoMap))
     return *AttrInfoMap[A.getParsedKind()];
 
   // If this is an ignored attribute then return an appropriate ParsedAttrInfo.
diff --git a/clang/unittests/AST/CommentLexer.cpp b/clang/unittests/AST/CommentLexer.cpp
--- a/clang/unittests/AST/CommentLexer.cpp
+++ b/clang/unittests/AST/CommentLexer.cpp
@@ -91,7 +91,7 @@
   const char *Sources[] = {
     "//", "///", "//!", "///<", "//!<"
   };
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     std::vector<Token> Toks;
 
     lexString(Sources[i], Toks);
@@ -107,7 +107,7 @@
   const char *Sources[] = {
     "/**/", "/***/", "/*!*/", "/**<*/", "/*!<*/"
   };
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     std::vector<Token> Toks;
 
     lexString(Sources[i], Toks);
@@ -126,7 +126,7 @@
     "// Meow\n", "// Meow\r\n", "//! Meow\r",
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     std::vector<Token> Toks;
 
     lexString(Sources[i], Toks);
@@ -146,7 +146,7 @@
     "/* Meow*/", "/** Meow*/",  "/*! Meow*/"
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     std::vector<Token> Toks;
 
     lexString(Sources[i], Toks);
@@ -169,7 +169,7 @@
     "// Aaa\\\r"   " Bbb\\ \r"   " Ccc?" "?/\r"
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     std::vector<Token> Toks;
 
     lexString(Sources[i], Toks);
@@ -248,7 +248,7 @@
 // A command marker followed by comment end.
 TEST_F(CommentLexerTest, DoxygenCommand1) {
   const char *Sources[] = { "//@", "///@", "//!@" };
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     std::vector<Token> Toks;
 
     lexString(Sources[i], Toks);
@@ -265,7 +265,7 @@
 // A command marker followed by comment end.
 TEST_F(CommentLexerTest, DoxygenCommand2) {
   const char *Sources[] = { "/*@*/", "/**@*/", "/*!@*/"};
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     std::vector<Token> Toks;
 
     lexString(Sources[i], Toks);
@@ -283,7 +283,7 @@
 // A command marker followed by comment end.
 TEST_F(CommentLexerTest, DoxygenCommand3) {
   const char *Sources[] = { "/*\\*/", "/**\\*/" };
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     std::vector<Token> Toks;
 
     lexString(Sources[i], Toks);
@@ -311,12 +311,12 @@
     "::", ""
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     std::vector<Token> Toks;
 
     lexString(Sources[i], Toks);
 
-    ASSERT_EQ(array_lengthof(Text), Toks.size());
+    ASSERT_EQ(std::size(Text), Toks.size());
 
     for (size_t j = 0, e = Toks.size(); j != e; j++) {
       if(Toks[j].is(tok::text)) {
@@ -578,7 +578,7 @@
     "/** \\verbatim\\endverbatim*/"
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     std::vector<Token> Toks;
 
     lexString(Sources[i], Toks);
@@ -645,7 +645,7 @@
     "/** Meow \\verbatim aaa \\endverbatim*/"
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     std::vector<Token> Toks;
 
     lexString(Sources[i], Toks);
@@ -676,7 +676,7 @@
     "/** Meow \\verbatim aaa */"
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     std::vector<Token> Toks;
 
     lexString(Sources[i], Toks);
@@ -901,7 +901,7 @@
     "/** \\fn*/"
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     std::vector<Token> Toks;
 
     lexString(Sources[i], Toks);
@@ -926,7 +926,7 @@
     "/** \\fn void *foo(const char *zzz = \"\\$\");*/"
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     std::vector<Token> Toks;
 
     lexString(Sources[i], Toks);
@@ -1052,7 +1052,7 @@
     "// <img "
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     std::vector<Token> Toks;
 
     lexString(Sources[i], Toks);
@@ -1169,7 +1169,7 @@
     "// <img src "
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     std::vector<Token> Toks;
 
     lexString(Sources[i], Toks);
@@ -1195,7 +1195,7 @@
     "// <img src ="
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     std::vector<Token> Toks;
 
     lexString(Sources[i], Toks);
@@ -1225,7 +1225,7 @@
     "// <img src = \'"
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     std::vector<Token> Toks;
 
     lexString(Sources[i], Toks);
@@ -1284,7 +1284,7 @@
     "// <img src=\'val\\\"\\'val\'"
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     std::vector<Token> Toks;
 
     lexString(Sources[i], Toks);
@@ -1315,7 +1315,7 @@
     "// <img src=\'val\\\"\\'val\'>"
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     std::vector<Token> Toks;
 
     lexString(Sources[i], Toks);
@@ -1348,7 +1348,7 @@
     "// <img />"
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     std::vector<Token> Toks;
 
     lexString(Sources[i], Toks);
@@ -1373,7 +1373,7 @@
     "// <img / Aaa"
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     std::vector<Token> Toks;
 
     lexString(Sources[i], Toks);
@@ -1797,7 +1797,7 @@
     "// &#X3D;"
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     std::vector<Token> Toks;
 
     lexString(Sources[i], Toks);
diff --git a/clang/unittests/AST/CommentParser.cpp b/clang/unittests/AST/CommentParser.cpp
--- a/clang/unittests/AST/CommentParser.cpp
+++ b/clang/unittests/AST/CommentParser.cpp
@@ -664,7 +664,7 @@
     "*/"),
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     FullComment *FC = parseString(Sources[i]);
     ASSERT_TRUE(HasChildCount(FC, 2));
 
@@ -801,7 +801,7 @@
     "// Bbb\n")
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     FullComment *FC = parseString(Sources[i]);
     ASSERT_TRUE(HasChildCount(FC, 2));
 
@@ -831,7 +831,7 @@
     "// Bbb\n"),
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     FullComment *FC = parseString(Sources[i]);
     ASSERT_TRUE(HasChildCount(FC, 2));
 
@@ -861,7 +861,7 @@
     "// Bbb\n"),
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     FullComment *FC = parseString(Sources[i]);
     ASSERT_TRUE(HasChildCount(FC, 2));
 
@@ -892,7 +892,7 @@
     "// Bbb\n"
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     FullComment *FC = parseString(Sources[i]);
     ASSERT_TRUE(HasChildCount(FC, 2));
 
@@ -947,7 +947,7 @@
     "// Bbb\n"
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     FullComment *FC = parseString(Sources[i]);
     ASSERT_TRUE(HasChildCount(FC, 2));
 
@@ -1081,7 +1081,7 @@
     "// <a >"
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     FullComment *FC = parseString(Sources[i]);
     ASSERT_TRUE(HasChildCount(FC, 1));
 
@@ -1103,7 +1103,7 @@
     "// <br />"
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     FullComment *FC = parseString(Sources[i]);
     ASSERT_TRUE(HasChildCount(FC, 1));
 
@@ -1127,7 +1127,7 @@
     "// <a href >",
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     FullComment *FC = parseString(Sources[i]);
     ASSERT_TRUE(HasChildCount(FC, 1));
 
@@ -1149,7 +1149,7 @@
     "// <a href=\"bbb\">",
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     FullComment *FC = parseString(Sources[i]);
     ASSERT_TRUE(HasChildCount(FC, 1));
 
@@ -1172,7 +1172,7 @@
     "// </a >"
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     FullComment *FC = parseString(Sources[i]);
     ASSERT_TRUE(HasChildCount(FC, 1));
 
@@ -1285,7 +1285,7 @@
     " *\\endverbatim*/"
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     FullComment *FC = parseString(Sources[i]);
     ASSERT_TRUE(HasChildCount(FC, 1));
 
@@ -1309,7 +1309,7 @@
     " * \\endverbatim*/"
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     FullComment *FC = parseString(Sources[i]);
     ASSERT_TRUE(HasChildCount(FC, 2));
 
@@ -1336,7 +1336,7 @@
     " * \\endverbatim*/"
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     FullComment *FC = parseString(Sources[i]);
     ASSERT_TRUE(HasChildCount(FC, 2));
 
@@ -1364,7 +1364,7 @@
     " * Bbb\n"
     " * \\endverbatim*/"
   };
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     FullComment *FC = parseString(Sources[i]);
     ASSERT_TRUE(HasChildCount(FC, 2));
 
@@ -1387,7 +1387,7 @@
     "// \\fn\n"
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     FullComment *FC = parseString(Sources[i]);
     ASSERT_TRUE(HasChildCount(FC, 2));
 
@@ -1405,7 +1405,7 @@
     "/** \\fn void *foo(const char *zzz = \"\\$\");*/"
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     FullComment *FC = parseString(Sources[i]);
     ASSERT_TRUE(HasChildCount(FC, 2));
 
@@ -1424,7 +1424,7 @@
     "/// @deprecated\n"
   };
 
-  for (size_t i = 0, e = array_lengthof(Sources); i != e; i++) {
+  for (size_t i = 0, e = std::size(Sources); i != e; i++) {
     FullComment *FC = parseString(Sources[i]);
     ASSERT_TRUE(HasChildCount(FC, 2));
 
diff --git a/clang/unittests/AST/DeclPrinterTest.cpp b/clang/unittests/AST/DeclPrinterTest.cpp
--- a/clang/unittests/AST/DeclPrinterTest.cpp
+++ b/clang/unittests/AST/DeclPrinterTest.cpp
@@ -731,7 +731,7 @@
     "()", "[]"
   };
 
-  for (unsigned i = 0, e = llvm::array_lengthof(OperatorNames); i != e; ++i) {
+  for (unsigned i = 0, e = std::size(OperatorNames); i != e; ++i) {
     SmallString<128> Code;
     Code.append("struct Z { void operator");
     Code.append(OperatorNames[i]);
@@ -754,7 +754,7 @@
     "~", "!", "++", "--", "->"
   };
 
-  for (unsigned i = 0, e = llvm::array_lengthof(OperatorNames); i != e; ++i) {
+  for (unsigned i = 0, e = std::size(OperatorNames); i != e; ++i) {
     SmallString<128> Code;
     Code.append("struct Z { void operator");
     Code.append(OperatorNames[i]);
diff --git a/clang/unittests/Tooling/CompilationDatabaseTest.cpp b/clang/unittests/Tooling/CompilationDatabaseTest.cpp
--- a/clang/unittests/Tooling/CompilationDatabaseTest.cpp
+++ b/clang/unittests/Tooling/CompilationDatabaseTest.cpp
@@ -642,7 +642,7 @@
   // Adjust the given command line arguments to ensure that any positional
   // arguments in them are stripped.
   const char *Argv[] = {"--", "somefile.cpp", "-fsyntax-only", "-DDEF3"};
-  int Argc = llvm::array_lengthof(Argv);
+  int Argc = std::size(Argv);
   std::string ErrorMessage;
   std::unique_ptr<CompilationDatabase> Database =
       FixedCompilationDatabase::loadFromCommandLine(Argc, Argv, ErrorMessage);