diff --git a/clang-tools-extra/clang-tidy/ClangTidyOptions.cpp b/clang-tools-extra/clang-tidy/ClangTidyOptions.cpp
index f532d3ea7a941..cbf21a0e2ae34 100644
--- a/clang-tools-extra/clang-tidy/ClangTidyOptions.cpp
+++ b/clang-tools-extra/clang-tidy/ClangTidyOptions.cpp
@@ -107,7 +107,7 @@ void yamlize(IO &IO, ClangTidyOptions::OptionMap &Val, bool,
   } else {
     // We need custom logic here to support the old method of specifying check
     // options using a list of maps containing key and value keys.
-    Input &I = reinterpret_cast<Input &>(IO);
+    auto &I = reinterpret_cast<Input &>(IO);
     if (isa<SequenceNode>(I.getCurrentNode())) {
       MappingNormalization<NOptionMap, ClangTidyOptions::OptionMap> NOpts(IO,
                                                                           Val);
@@ -134,7 +134,7 @@ template <> void yamlize(IO &IO, ChecksVariant &Val, bool, EmptyContext &Ctx) {
   if (!IO.outputting()) {
     // Special case for reading from YAML
     // Must support reading from both a string or a list
-    Input &I = reinterpret_cast<Input &>(IO);
+    auto &I = reinterpret_cast<Input &>(IO);
     if (isa<ScalarNode, BlockScalarNode>(I.getCurrentNode())) {
       Val.AsString = std::string();
       yamlize(IO, *Val.AsString, true, Ctx);
diff --git a/clang-tools-extra/clang-tidy/abseil/DurationAdditionCheck.cpp b/clang-tools-extra/clang-tidy/abseil/DurationAdditionCheck.cpp
index 2a31d60961703..d4b8c9e6d8942 100644
--- a/clang-tools-extra/clang-tidy/abseil/DurationAdditionCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/DurationAdditionCheck.cpp
@@ -29,9 +29,8 @@ void DurationAdditionCheck::registerMatchers(MatchFinder *Finder) {
 }
 
 void DurationAdditionCheck::check(const MatchFinder::MatchResult &Result) {
-  const BinaryOperator *Binop =
-      Result.Nodes.getNodeAs<clang::BinaryOperator>("binop");
-  const CallExpr *Call = Result.Nodes.getNodeAs<clang::CallExpr>("call");
+  const auto *Binop = Result.Nodes.getNodeAs<clang::BinaryOperator>("binop");
+  const auto *Call = Result.Nodes.getNodeAs<clang::CallExpr>("call");
 
   // Don't try to replace things inside of macro definitions.
   if (Binop->getExprLoc().isMacroID() || Binop->getExprLoc().isInvalid())
diff --git a/clang-tools-extra/clang-tidy/abseil/StringFindStartswithCheck.cpp b/clang-tools-extra/clang-tidy/abseil/StringFindStartswithCheck.cpp
index 7effb8250ae76..b36144d1912fc 100644
--- a/clang-tools-extra/clang-tidy/abseil/StringFindStartswithCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/StringFindStartswithCheck.cpp
@@ -86,8 +86,7 @@ void StringFindStartswithCheck::check(const MatchFinder::MatchResult &Result) {
   const Expr *Haystack = Result.Nodes.getNodeAs<CXXMemberCallExpr>("findexpr")
                              ->getImplicitObjectArgument();
   assert(Haystack != nullptr);
-  const CXXMethodDecl *FindFun =
-      Result.Nodes.getNodeAs<CXXMethodDecl>("findfun");
+  const auto *FindFun = Result.Nodes.getNodeAs<CXXMethodDecl>("findfun");
   assert(FindFun != nullptr);
 
   bool Rev = FindFun->getName().contains("rfind");
diff --git a/clang-tools-extra/clang-tidy/altera/StructPackAlignCheck.cpp b/clang-tools-extra/clang-tidy/altera/StructPackAlignCheck.cpp
index c3b47d41c46d6..cdaedd440959c 100644
--- a/clang-tools-extra/clang-tidy/altera/StructPackAlignCheck.cpp
+++ b/clang-tools-extra/clang-tidy/altera/StructPackAlignCheck.cpp
@@ -110,7 +110,7 @@ void StructPackAlignCheck::check(const MatchFinder::MatchResult &Result) {
   }
 
   FixItHint FixIt;
-  AlignedAttr *Attribute = Struct->getAttr<AlignedAttr>();
+  auto *Attribute = Struct->getAttr<AlignedAttr>();
   std::string NewAlignQuantity = std::to_string((int)NewAlign.getQuantity());
   if (Attribute) {
     FixIt = FixItHint::CreateReplacement(
diff --git a/clang-tools-extra/clang-tidy/bugprone/BranchCloneCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/BranchCloneCheck.cpp
index d27fe0c08d72b..356acf968db92 100644
--- a/clang-tools-extra/clang-tidy/bugprone/BranchCloneCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/BranchCloneCheck.cpp
@@ -196,7 +196,7 @@ void BranchCloneCheck::check(const MatchFinder::MatchResult &Result) {
   }
 
   if (const auto *SS = Result.Nodes.getNodeAs<SwitchStmt>("switch")) {
-    const CompoundStmt *Body = dyn_cast_or_null<CompoundStmt>(SS->getBody());
+    const auto *Body = dyn_cast_or_null<CompoundStmt>(SS->getBody());
 
     // Code like
     //   switch (x) case 0: case 1: foobar();
diff --git a/clang-tools-extra/clang-tidy/bugprone/StandaloneEmptyCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/StandaloneEmptyCheck.cpp
index a66f838f1c8fa..2bce72cca98c6 100644
--- a/clang-tools-extra/clang-tidy/bugprone/StandaloneEmptyCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/StandaloneEmptyCheck.cpp
@@ -135,7 +135,7 @@ void StandaloneEmptyCheck::check(const MatchFinder::MatchResult &Result) {
 
     bool HasClear = !Candidates.empty();
     if (HasClear) {
-      const CXXMethodDecl *Clear = llvm::cast<CXXMethodDecl>(Candidates.at(0));
+      const auto *Clear = llvm::cast<CXXMethodDecl>(Candidates.at(0));
       QualType RangeType = MemberCall->getImplicitObjectArgument()->getType();
       bool QualifierIncompatible =
           (!Clear->isVolatile() && RangeType.isVolatileQualified()) ||
@@ -185,7 +185,7 @@ void StandaloneEmptyCheck::check(const MatchFinder::MatchResult &Result) {
     bool HasClear = !Candidates.empty();
 
     if (HasClear) {
-      const CXXMethodDecl *Clear = llvm::cast<CXXMethodDecl>(Candidates.at(0));
+      const auto *Clear = llvm::cast<CXXMethodDecl>(Candidates.at(0));
       bool QualifierIncompatible =
           (!Clear->isVolatile() && Arg->getType().isVolatileQualified()) ||
           Arg->getType().isConstQualified();
diff --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeMemberInitCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeMemberInitCheck.cpp
index ff5a750a8dac4..7af096053e9e2 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeMemberInitCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeMemberInitCheck.cpp
@@ -381,8 +381,7 @@ static const char *getInitializer(QualType QT, bool UseAssignment) {
   if (QT->isPointerType())
     return " = nullptr";
 
-  const BuiltinType *BT =
-      dyn_cast<BuiltinType>(QT.getCanonicalType().getTypePtr());
+  const auto *BT = dyn_cast<BuiltinType>(QT.getCanonicalType().getTypePtr());
   if (!BT)
     return DefaultInitializer;
 
diff --git a/clang-tools-extra/clang-tidy/linuxkernel/MustCheckErrsCheck.cpp b/clang-tools-extra/clang-tidy/linuxkernel/MustCheckErrsCheck.cpp
index 400ec0d4fabed..3889fd536f2dc 100644
--- a/clang-tools-extra/clang-tidy/linuxkernel/MustCheckErrsCheck.cpp
+++ b/clang-tools-extra/clang-tidy/linuxkernel/MustCheckErrsCheck.cpp
@@ -31,13 +31,13 @@ void MustCheckErrsCheck::registerMatchers(MatchFinder *Finder) {
 }
 
 void MustCheckErrsCheck::check(const MatchFinder::MatchResult &Result) {
-  const CallExpr *MatchedCallExpr = Result.Nodes.getNodeAs<CallExpr>("call");
+  const auto *MatchedCallExpr = Result.Nodes.getNodeAs<CallExpr>("call");
   if (MatchedCallExpr) {
     diag(MatchedCallExpr->getExprLoc(), "result from function %0 is unused")
         << MatchedCallExpr->getDirectCallee();
   }
 
-  const CallExpr *MatchedTransitiveCallExpr =
+  const auto *MatchedTransitiveCallExpr =
       Result.Nodes.getNodeAs<CallExpr>("transitive_call");
   if (MatchedTransitiveCallExpr) {
     diag(MatchedTransitiveCallExpr->getExprLoc(),
diff --git a/clang-tools-extra/clang-tidy/misc/ConfusableIdentifierCheck.cpp b/clang-tools-extra/clang-tidy/misc/ConfusableIdentifierCheck.cpp
index c2f72c8fc20a0..551f26ab9b924 100644
--- a/clang-tools-extra/clang-tidy/misc/ConfusableIdentifierCheck.cpp
+++ b/clang-tools-extra/clang-tidy/misc/ConfusableIdentifierCheck.cpp
@@ -161,7 +161,7 @@ ConfusableIdentifierCheck::getContextInfo(const DeclContext *DC) {
     DC = DC->getParent();
   }
 
-  if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(PrimaryContext)) {
+  if (const auto *RD = dyn_cast<CXXRecordDecl>(PrimaryContext)) {
     RD = RD->getDefinition();
     if (RD) {
       Info.Bases.push_back(RD);
diff --git a/clang-tools-extra/clang-tidy/modernize/PassByValueCheck.cpp b/clang-tools-extra/clang-tidy/modernize/PassByValueCheck.cpp
index ff3b3a7ce5c39..815c02a15492d 100644
--- a/clang-tools-extra/clang-tidy/modernize/PassByValueCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/PassByValueCheck.cpp
@@ -269,7 +269,7 @@ void PassByValueCheck::check(const MatchFinder::MatchResult &Result) {
     // Check if we can succesfully rewrite all declarations of the constructor.
     for (const ParmVarDecl *ParmDecl : collectParamDecls(Ctor, ParamDecl)) {
       TypeLoc ParamTL = ParmDecl->getTypeSourceInfo()->getTypeLoc();
-      ReferenceTypeLoc RefTL = ParamTL.getAs<ReferenceTypeLoc>();
+      auto RefTL = ParamTL.getAs<ReferenceTypeLoc>();
       if (RefTL.isNull()) {
         // We cannot rewrite this instance. The type is probably hidden behind
         // some `typedef`. Do not offer a fix-it in this case.
@@ -279,7 +279,7 @@ void PassByValueCheck::check(const MatchFinder::MatchResult &Result) {
     // Rewrite all declarations.
     for (const ParmVarDecl *ParmDecl : collectParamDecls(Ctor, ParamDecl)) {
       TypeLoc ParamTL = ParmDecl->getTypeSourceInfo()->getTypeLoc();
-      ReferenceTypeLoc RefTL = ParamTL.getAs<ReferenceTypeLoc>();
+      auto RefTL = ParamTL.getAs<ReferenceTypeLoc>();
 
       TypeLoc ValueTL = RefTL.getPointeeLoc();
       CharSourceRange TypeRange = CharSourceRange::getTokenRange(
diff --git a/clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp
index 00c7d419037fe..b81cfbcbfd16c 100644
--- a/clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp
@@ -434,8 +434,7 @@ void UseTrailingReturnTypeCheck::check(const MatchFinder::MatchResult &Result) {
   if (!TSI)
     return;
 
-  FunctionTypeLoc FTL =
-      TSI->getTypeLoc().IgnoreParens().getAs<FunctionTypeLoc>();
+  auto FTL = TSI->getTypeLoc().IgnoreParens().getAs<FunctionTypeLoc>();
   if (!FTL) {
     // FIXME: This may happen if we have __attribute__((...)) on the function.
     // We abort for now. Remove this when the function type location gets
diff --git a/clang-tools-extra/clang-tidy/modernize/UseUncaughtExceptionsCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UseUncaughtExceptionsCheck.cpp
index 06a2778b46dd7..cffb931afa2d8 100644
--- a/clang-tools-extra/clang-tidy/modernize/UseUncaughtExceptionsCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/UseUncaughtExceptionsCheck.cpp
@@ -49,7 +49,7 @@ void UseUncaughtExceptionsCheck::registerMatchers(MatchFinder *Finder) {
 void UseUncaughtExceptionsCheck::check(const MatchFinder::MatchResult &Result) {
   SourceLocation BeginLoc;
   SourceLocation EndLoc;
-  const CallExpr *C = Result.Nodes.getNodeAs<CallExpr>("init_call_expr");
+  const auto *C = Result.Nodes.getNodeAs<CallExpr>("init_call_expr");
   bool WarnOnly = false;
 
   if (C) {
diff --git a/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.cpp b/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.cpp
index 102980d8dd10b..e875717da247e 100644
--- a/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.cpp
@@ -649,7 +649,7 @@ std::string IdentifierNamingCheck::HungarianNotation::getClassPrefix(
 
 std::string IdentifierNamingCheck::HungarianNotation::getEnumPrefix(
     const EnumConstantDecl *ECD) const {
-  const EnumDecl *ED = cast<EnumDecl>(ECD->getDeclContext());
+  const auto *ED = cast<EnumDecl>(ECD->getDeclContext());
 
   std::string Name = ED->getName().str();
   if (std::string::npos != Name.find("enum")) {
diff --git a/clang-tools-extra/clang-tidy/readability/MakeMemberFunctionConstCheck.cpp b/clang-tools-extra/clang-tidy/readability/MakeMemberFunctionConstCheck.cpp
index 2d6a469252425..d42fcba70e81b 100644
--- a/clang-tools-extra/clang-tidy/readability/MakeMemberFunctionConstCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/MakeMemberFunctionConstCheck.cpp
@@ -241,8 +241,7 @@ static SourceLocation getConstInsertionPoint(const CXXMethodDecl *M) {
   if (!TSI)
     return {};
 
-  FunctionTypeLoc FTL =
-      TSI->getTypeLoc().IgnoreParens().getAs<FunctionTypeLoc>();
+  auto FTL = TSI->getTypeLoc().IgnoreParens().getAs<FunctionTypeLoc>();
   if (!FTL)
     return {};