diff --git a/clang/include/clang/AST/APValue.h b/clang/include/clang/AST/APValue.h
index 833a78c77871d..9999a30c51ade 100644
--- a/clang/include/clang/AST/APValue.h
+++ b/clang/include/clang/AST/APValue.h
@@ -161,8 +161,9 @@ class APValue {
 
     template <class T> T get() const { return cast<T>(Ptr); }
 
-    template <class T>
-    T dyn_cast() const { return Ptr.dyn_cast<T>(); }
+    template <class T> T dyn_cast() const {
+      return dyn_cast_if_present<T>(Ptr);
+    }
 
     void *getOpaqueValue() const;
 
diff --git a/clang/include/clang/AST/ASTContext.h b/clang/include/clang/AST/ASTContext.h
index 4e9b961688d55..65be782c1ba43 100644
--- a/clang/include/clang/AST/ASTContext.h
+++ b/clang/include/clang/AST/ASTContext.h
@@ -769,7 +769,7 @@ class ASTContext : public RefCountedBase<ASTContext> {
   /// pool.
   DeclListNode *AllocateDeclListNode(clang::NamedDecl *ND) {
     if (DeclListNode *Alloc = ListNodeFreeList) {
-      ListNodeFreeList = Alloc->Rest.dyn_cast<DeclListNode*>();
+      ListNodeFreeList = dyn_cast_if_present<DeclListNode *>(Alloc->Rest);
       Alloc->D = ND;
       Alloc->Rest = nullptr;
       return Alloc;
diff --git a/clang/include/clang/AST/Decl.h b/clang/include/clang/AST/Decl.h
index d01681483a918..16403774e72b3 100644
--- a/clang/include/clang/AST/Decl.h
+++ b/clang/include/clang/AST/Decl.h
@@ -4035,7 +4035,7 @@ class EnumDecl : public TagDecl {
   /// Return the type source info for the underlying integer type,
   /// if no type source info exists, return 0.
   TypeSourceInfo *getIntegerTypeSourceInfo() const {
-    return IntegerType.dyn_cast<TypeSourceInfo*>();
+    return dyn_cast_if_present<TypeSourceInfo *>(IntegerType);
   }
 
   /// Retrieve the source range that covers the underlying type if
diff --git a/clang/include/clang/AST/DeclBase.h b/clang/include/clang/AST/DeclBase.h
index 573b46a2321c5..2c0c3a8dc2f9d 100644
--- a/clang/include/clang/AST/DeclBase.h
+++ b/clang/include/clang/AST/DeclBase.h
@@ -1391,7 +1391,7 @@ class DeclContextLookupResult {
   const_iterator end() const { return iterator(); }
 
   bool empty() const { return Result.isNull();  }
-  bool isSingleResult() const { return Result.dyn_cast<NamedDecl*>(); }
+  bool isSingleResult() const { return isa_and_present<NamedDecl *>(Result); }
   reference front() const { return *begin(); }
 
   // Find the first declaration of the given type in the list. Note that this
diff --git a/clang/include/clang/AST/DeclTemplate.h b/clang/include/clang/AST/DeclTemplate.h
index 8c2da97c07a3b..caaa47d0a297c 100644
--- a/clang/include/clang/AST/DeclTemplate.h
+++ b/clang/include/clang/AST/DeclTemplate.h
@@ -2009,7 +2009,8 @@ class ClassTemplateSpecializationDecl : public CXXRecordDecl,
   /// Retrieve the template argument list as written in the sources,
   /// if any.
   const ASTTemplateArgumentListInfo *getTemplateArgsAsWritten() const {
-    if (auto *Info = ExplicitInfo.dyn_cast<ExplicitInstantiationInfo *>())
+    if (auto *Info =
+            dyn_cast_if_present<ExplicitInstantiationInfo *>(ExplicitInfo))
       return Info->TemplateArgsAsWritten;
     return cast<const ASTTemplateArgumentListInfo *>(ExplicitInfo);
   }
@@ -2041,7 +2042,8 @@ class ClassTemplateSpecializationDecl : public CXXRecordDecl,
 
   /// Gets the location of the template keyword, if present.
   SourceLocation getTemplateKeywordLoc() const {
-    if (auto *Info = ExplicitInfo.dyn_cast<ExplicitInstantiationInfo *>())
+    if (auto *Info =
+            dyn_cast_if_present<ExplicitInstantiationInfo *>(ExplicitInfo))
       return Info->TemplateKeywordLoc;
     return SourceLocation();
   }
@@ -2786,7 +2788,8 @@ class VarTemplateSpecializationDecl : public VarDecl,
   /// Set the template argument list as written in the sources.
   void
   setTemplateArgsAsWritten(const ASTTemplateArgumentListInfo *ArgsWritten) {
-    if (auto *Info = ExplicitInfo.dyn_cast<ExplicitInstantiationInfo *>())
+    if (auto *Info =
+            dyn_cast_if_present<ExplicitInstantiationInfo *>(ExplicitInfo))
       Info->TemplateArgsAsWritten = ArgsWritten;
     else
       ExplicitInfo = ArgsWritten;
diff --git a/clang/include/clang/AST/Expr.h b/clang/include/clang/AST/Expr.h
index 708c8656decbe..7be4022649329 100644
--- a/clang/include/clang/AST/Expr.h
+++ b/clang/include/clang/AST/Expr.h
@@ -5180,7 +5180,7 @@ class InitListExpr : public Expr {
   /// than there are initializers in the list, specifies an expression to be
   /// used for value initialization of the rest of the elements.
   Expr *getArrayFiller() {
-    return ArrayFillerOrUnionFieldInit.dyn_cast<Expr *>();
+    return dyn_cast_if_present<Expr *>(ArrayFillerOrUnionFieldInit);
   }
   const Expr *getArrayFiller() const {
     return const_cast<InitListExpr *>(this)->getArrayFiller();
@@ -5205,7 +5205,7 @@ class InitListExpr : public Expr {
   /// union. However, a designated initializer can specify the
   /// initialization of a different field within the union.
   FieldDecl *getInitializedFieldInUnion() {
-    return ArrayFillerOrUnionFieldInit.dyn_cast<FieldDecl *>();
+    return dyn_cast_if_present<FieldDecl *>(ArrayFillerOrUnionFieldInit);
   }
   const FieldDecl *getInitializedFieldInUnion() const {
     return const_cast<InitListExpr *>(this)->getInitializedFieldInUnion();
diff --git a/clang/include/clang/AST/ExprCXX.h b/clang/include/clang/AST/ExprCXX.h
index 4cec89c979f77..aa10945addf78 100644
--- a/clang/include/clang/AST/ExprCXX.h
+++ b/clang/include/clang/AST/ExprCXX.h
@@ -5026,11 +5026,11 @@ class CXXParenListInitExpr final
   void setArrayFiller(Expr *E) { ArrayFillerOrUnionFieldInit = E; }
 
   Expr *getArrayFiller() {
-    return ArrayFillerOrUnionFieldInit.dyn_cast<Expr *>();
+    return dyn_cast_if_present<Expr *>(ArrayFillerOrUnionFieldInit);
   }
 
   const Expr *getArrayFiller() const {
-    return ArrayFillerOrUnionFieldInit.dyn_cast<Expr *>();
+    return dyn_cast_if_present<Expr *>(ArrayFillerOrUnionFieldInit);
   }
 
   void setInitializedFieldInUnion(FieldDecl *FD) {
@@ -5038,7 +5038,7 @@ class CXXParenListInitExpr final
   }
 
   FieldDecl *getInitializedFieldInUnion() {
-    return ArrayFillerOrUnionFieldInit.dyn_cast<FieldDecl *>();
+    return dyn_cast_if_present<FieldDecl *>(ArrayFillerOrUnionFieldInit);
   }
 
   const FieldDecl *getInitializedFieldInUnion() const {
diff --git a/clang/include/clang/Basic/IdentifierTable.h b/clang/include/clang/Basic/IdentifierTable.h
index 33d1cdb46f108..e5e6be3c96600 100644
--- a/clang/include/clang/Basic/IdentifierTable.h
+++ b/clang/include/clang/Basic/IdentifierTable.h
@@ -1008,7 +1008,7 @@ class Selector {
   }
 
   const IdentifierInfo *getAsIdentifierInfo() const {
-    return InfoPtr.getPointer().dyn_cast<const IdentifierInfo *>();
+    return dyn_cast_if_present<const IdentifierInfo *>(InfoPtr.getPointer());
   }
 
   MultiKeywordSelector *getMultiKeywordSelector() const {
diff --git a/clang/include/clang/Lex/Preprocessor.h b/clang/include/clang/Lex/Preprocessor.h
index 8ddc5b56eedbd..416f403c29841 100644
--- a/clang/include/clang/Lex/Preprocessor.h
+++ b/clang/include/clang/Lex/Preprocessor.h
@@ -856,7 +856,7 @@ class Preprocessor {
           !PP.CurSubmoduleState->VisibleModules.getGeneration())
         return nullptr;
 
-      auto *Info = State.dyn_cast<ModuleMacroInfo*>();
+      auto *Info = dyn_cast_if_present<ModuleMacroInfo *>(State);
       if (!Info) {
         Info = new (PP.getPreprocessorAllocator())
             ModuleMacroInfo(cast<MacroDirective *>(State));
@@ -885,18 +885,18 @@ class Preprocessor {
     }
 
     ~MacroState() {
-      if (auto *Info = State.dyn_cast<ModuleMacroInfo*>())
+      if (auto *Info = dyn_cast_if_present<ModuleMacroInfo *>(State))
         Info->~ModuleMacroInfo();
     }
 
     MacroDirective *getLatest() const {
-      if (auto *Info = State.dyn_cast<ModuleMacroInfo*>())
+      if (auto *Info = dyn_cast_if_present<ModuleMacroInfo *>(State))
         return Info->MD;
       return cast<MacroDirective *>(State);
     }
 
     void setLatest(MacroDirective *MD) {
-      if (auto *Info = State.dyn_cast<ModuleMacroInfo*>())
+      if (auto *Info = dyn_cast_if_present<ModuleMacroInfo *>(State))
         Info->MD = MD;
       else
         State = MD;
@@ -940,7 +940,7 @@ class Preprocessor {
 
     void setOverriddenMacros(Preprocessor &PP,
                              ArrayRef<ModuleMacro *> Overrides) {
-      auto *Info = State.dyn_cast<ModuleMacroInfo*>();
+      auto *Info = dyn_cast_if_present<ModuleMacroInfo *>(State);
       if (!Info) {
         if (Overrides.empty())
           return;
diff --git a/clang/lib/APINotes/APINotesManager.cpp b/clang/lib/APINotes/APINotesManager.cpp
index 70d96c735503f..7f8a126ffaa03 100644
--- a/clang/lib/APINotes/APINotesManager.cpp
+++ b/clang/lib/APINotes/APINotesManager.cpp
@@ -56,7 +56,7 @@ APINotesManager::APINotesManager(SourceManager &SM, const LangOptions &LangOpts)
 APINotesManager::~APINotesManager() {
   // Free the API notes readers.
   for (const auto &Entry : Readers) {
-    if (auto Reader = Entry.second.dyn_cast<APINotesReader *>())
+    if (auto Reader = dyn_cast_if_present<APINotesReader *>(Entry.second))
       delete Reader;
   }
 
@@ -381,7 +381,7 @@ APINotesManager::findAPINotes(SourceLocation Loc) {
       }
 
       // We have the answer.
-      if (auto Reader = Known->second.dyn_cast<APINotesReader *>())
+      if (auto Reader = dyn_cast_if_present<APINotesReader *>(Known->second))
         Results.push_back(Reader);
       break;
     }
diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index 5ce03ce20d284..74bcb618f2950 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -2447,7 +2447,7 @@ bool VarDecl::isOutOfLine() const {
 }
 
 void VarDecl::setInit(Expr *I) {
-  if (auto *Eval = Init.dyn_cast<EvaluatedStmt *>()) {
+  if (auto *Eval = dyn_cast_if_present<EvaluatedStmt *>(Init)) {
     Eval->~EvaluatedStmt();
     getASTContext().Deallocate(Eval);
   }
@@ -2527,7 +2527,7 @@ bool VarDecl::isUsableInConstantExpressions(const ASTContext &Context) const {
 /// form, which contains extra information on the evaluated value of the
 /// initializer.
 EvaluatedStmt *VarDecl::ensureEvaluatedStmt() const {
-  auto *Eval = Init.dyn_cast<EvaluatedStmt *>();
+  auto *Eval = dyn_cast_if_present<EvaluatedStmt *>(Init);
   if (!Eval) {
     // Note: EvaluatedStmt contains an APValue, which usually holds
     // resources not allocated from the ASTContext.  We need to do some
@@ -2541,7 +2541,7 @@ EvaluatedStmt *VarDecl::ensureEvaluatedStmt() const {
 }
 
 EvaluatedStmt *VarDecl::getEvaluatedStmt() const {
-  return Init.dyn_cast<EvaluatedStmt *>();
+  return dyn_cast_if_present<EvaluatedStmt *>(Init);
 }
 
 APValue *VarDecl::evaluateValue() const {
@@ -2784,8 +2784,8 @@ SourceLocation VarDecl::getPointOfInstantiation() const {
 }
 
 VarTemplateDecl *VarDecl::getDescribedVarTemplate() const {
-  return getASTContext().getTemplateOrSpecializationInfo(this)
-      .dyn_cast<VarTemplateDecl *>();
+  return dyn_cast_if_present<VarTemplateDecl *>(
+      getASTContext().getTemplateOrSpecializationInfo(this));
 }
 
 void VarDecl::setDescribedVarTemplate(VarTemplateDecl *Template) {
@@ -2875,8 +2875,8 @@ MemberSpecializationInfo *VarDecl::getMemberSpecializationInfo() const {
   if (isStaticDataMember())
     // FIXME: Remove ?
     // return getASTContext().getInstantiatedFromStaticDataMember(this);
-    return getASTContext().getTemplateOrSpecializationInfo(this)
-        .dyn_cast<MemberSpecializationInfo *>();
+    return dyn_cast_if_present<MemberSpecializationInfo *>(
+        getASTContext().getTemplateOrSpecializationInfo(this));
   return nullptr;
 }
 
@@ -4040,11 +4040,11 @@ FunctionDecl *FunctionDecl::getInstantiatedFromMemberFunction() const {
 }
 
 MemberSpecializationInfo *FunctionDecl::getMemberSpecializationInfo() const {
-  if (auto *MSI =
-          TemplateOrSpecialization.dyn_cast<MemberSpecializationInfo *>())
+  if (auto *MSI = dyn_cast_if_present<MemberSpecializationInfo *>(
+          TemplateOrSpecialization))
     return MSI;
-  if (auto *FTSI = TemplateOrSpecialization
-                       .dyn_cast<FunctionTemplateSpecializationInfo *>())
+  if (auto *FTSI = dyn_cast_if_present<FunctionTemplateSpecializationInfo *>(
+          TemplateOrSpecialization))
     return FTSI->getMemberSpecializationInfo();
   return nullptr;
 }
@@ -4062,7 +4062,7 @@ FunctionDecl::setInstantiationOfMemberFunction(ASTContext &C,
 
 FunctionTemplateDecl *FunctionDecl::getDescribedFunctionTemplate() const {
   return dyn_cast_if_present<FunctionTemplateDecl>(
-      TemplateOrSpecialization.dyn_cast<NamedDecl *>());
+      dyn_cast_if_present<NamedDecl *>(TemplateOrSpecialization));
 }
 
 void FunctionDecl::setDescribedFunctionTemplate(
@@ -4181,9 +4181,9 @@ FunctionDecl::getTemplateInstantiationPattern(bool ForDefinition) const {
 }
 
 FunctionTemplateDecl *FunctionDecl::getPrimaryTemplate() const {
-  if (FunctionTemplateSpecializationInfo *Info
-        = TemplateOrSpecialization
-            .dyn_cast<FunctionTemplateSpecializationInfo*>()) {
+  if (FunctionTemplateSpecializationInfo *Info =
+          dyn_cast_if_present<FunctionTemplateSpecializationInfo *>(
+              TemplateOrSpecialization)) {
     return Info->getTemplate();
   }
   return nullptr;
@@ -4191,15 +4191,15 @@ FunctionTemplateDecl *FunctionDecl::getPrimaryTemplate() const {
 
 FunctionTemplateSpecializationInfo *
 FunctionDecl::getTemplateSpecializationInfo() const {
-  return TemplateOrSpecialization
-      .dyn_cast<FunctionTemplateSpecializationInfo *>();
+  return dyn_cast_if_present<FunctionTemplateSpecializationInfo *>(
+      TemplateOrSpecialization);
 }
 
 const TemplateArgumentList *
 FunctionDecl::getTemplateSpecializationArgs() const {
-  if (FunctionTemplateSpecializationInfo *Info
-        = TemplateOrSpecialization
-            .dyn_cast<FunctionTemplateSpecializationInfo*>()) {
+  if (FunctionTemplateSpecializationInfo *Info =
+          dyn_cast_if_present<FunctionTemplateSpecializationInfo *>(
+              TemplateOrSpecialization)) {
     return Info->TemplateArguments;
   }
   return nullptr;
@@ -4207,14 +4207,14 @@ FunctionDecl::getTemplateSpecializationArgs() const {
 
 const ASTTemplateArgumentListInfo *
 FunctionDecl::getTemplateSpecializationArgsAsWritten() const {
-  if (FunctionTemplateSpecializationInfo *Info
-        = TemplateOrSpecialization
-            .dyn_cast<FunctionTemplateSpecializationInfo*>()) {
+  if (FunctionTemplateSpecializationInfo *Info =
+          dyn_cast_if_present<FunctionTemplateSpecializationInfo *>(
+              TemplateOrSpecialization)) {
     return Info->TemplateArgumentsAsWritten;
   }
   if (DependentFunctionTemplateSpecializationInfo *Info =
-          TemplateOrSpecialization
-              .dyn_cast<DependentFunctionTemplateSpecializationInfo *>()) {
+          dyn_cast_if_present<DependentFunctionTemplateSpecializationInfo *>(
+              TemplateOrSpecialization)) {
     return Info->TemplateArgumentsAsWritten;
   }
   return nullptr;
@@ -4239,7 +4239,8 @@ void FunctionDecl::setFunctionTemplateSpecialization(
       FunctionTemplateSpecializationInfo::Create(
           C, this, Template, TSK, TemplateArgs, TemplateArgsAsWritten,
           PointOfInstantiation,
-          TemplateOrSpecialization.dyn_cast<MemberSpecializationInfo *>());
+          dyn_cast_if_present<MemberSpecializationInfo *>(
+              TemplateOrSpecialization));
   TemplateOrSpecialization = Info;
   Template->addSpecialization(Info, InsertPos);
 }
@@ -4256,8 +4257,8 @@ void FunctionDecl::setDependentTemplateSpecialization(
 
 DependentFunctionTemplateSpecializationInfo *
 FunctionDecl::getDependentSpecializationInfo() const {
-  return TemplateOrSpecialization
-      .dyn_cast<DependentFunctionTemplateSpecializationInfo *>();
+  return dyn_cast_if_present<DependentFunctionTemplateSpecializationInfo *>(
+      TemplateOrSpecialization);
 }
 
 DependentFunctionTemplateSpecializationInfo *
@@ -4288,12 +4289,13 @@ TemplateSpecializationKind FunctionDecl::getTemplateSpecializationKind() const {
   // For a function template specialization, query the specialization
   // information object.
   if (FunctionTemplateSpecializationInfo *FTSInfo =
-          TemplateOrSpecialization
-              .dyn_cast<FunctionTemplateSpecializationInfo *>())
+          dyn_cast_if_present<FunctionTemplateSpecializationInfo *>(
+              TemplateOrSpecialization))
     return FTSInfo->getTemplateSpecializationKind();
 
   if (MemberSpecializationInfo *MSInfo =
-          TemplateOrSpecialization.dyn_cast<MemberSpecializationInfo *>())
+          dyn_cast_if_present<MemberSpecializationInfo *>(
+              TemplateOrSpecialization))
     return MSInfo->getTemplateSpecializationKind();
 
   // A dependent function template specialization is an explicit specialization,
@@ -4331,15 +4333,16 @@ FunctionDecl::getTemplateSpecializationKindForInstantiation() const {
   // of A<int>::f, and that A<int>::f<int> should be implicitly instantiated
   // from A::f<int> if a definition is needed.
   if (FunctionTemplateSpecializationInfo *FTSInfo =
-          TemplateOrSpecialization
-              .dyn_cast<FunctionTemplateSpecializationInfo *>()) {
+          dyn_cast_if_present<FunctionTemplateSpecializationInfo *>(
+              TemplateOrSpecialization)) {
     if (auto *MSInfo = FTSInfo->getMemberSpecializationInfo())
       return MSInfo->getTemplateSpecializationKind();
     return FTSInfo->getTemplateSpecializationKind();
   }
 
   if (MemberSpecializationInfo *MSInfo =
-          TemplateOrSpecialization.dyn_cast<MemberSpecializationInfo *>())
+          dyn_cast_if_present<MemberSpecializationInfo *>(
+              TemplateOrSpecialization))
     return MSInfo->getTemplateSpecializationKind();
 
   if (isa<DependentFunctionTemplateSpecializationInfo *>(
diff --git a/clang/lib/AST/DeclCXX.cpp b/clang/lib/AST/DeclCXX.cpp
index 44f45898fb483..c0a4356dcb004 100644
--- a/clang/lib/AST/DeclCXX.cpp
+++ b/clang/lib/AST/DeclCXX.cpp
@@ -1987,7 +1987,8 @@ CXXRecordDecl *CXXRecordDecl::getInstantiatedFromMemberClass() const {
 }
 
 MemberSpecializationInfo *CXXRecordDecl::getMemberSpecializationInfo() const {
-  return TemplateOrInstantiation.dyn_cast<MemberSpecializationInfo *>();
+  return dyn_cast_if_present<MemberSpecializationInfo *>(
+      TemplateOrInstantiation);
 }
 
 void
@@ -2001,7 +2002,7 @@ CXXRecordDecl::setInstantiationOfMemberClass(CXXRecordDecl *RD,
 }
 
 ClassTemplateDecl *CXXRecordDecl::getDescribedClassTemplate() const {
-  return TemplateOrInstantiation.dyn_cast<ClassTemplateDecl *>();
+  return dyn_cast_if_present<ClassTemplateDecl *>(TemplateOrInstantiation);
 }
 
 void CXXRecordDecl::setDescribedClassTemplate(ClassTemplateDecl *Template) {
@@ -2045,7 +2046,7 @@ const CXXRecordDecl *CXXRecordDecl::getTemplateInstantiationPattern() const {
   // specialization from which it was instantiated.
   if (auto *TD = dyn_cast<ClassTemplateSpecializationDecl>(this)) {
     auto From = TD->getInstantiatedFrom();
-    if (auto *CTD = From.dyn_cast<ClassTemplateDecl *>()) {
+    if (auto *CTD = dyn_cast_if_present<ClassTemplateDecl *>(From)) {
       while (auto *NewCTD = CTD->getInstantiatedFromMemberTemplate()) {
         if (NewCTD->isMemberSpecialization())
           break;
@@ -2054,7 +2055,8 @@ const CXXRecordDecl *CXXRecordDecl::getTemplateInstantiationPattern() const {
       return GetDefinitionOrSelf(CTD->getTemplatedDecl());
     }
     if (auto *CTPSD =
-            From.dyn_cast<ClassTemplatePartialSpecializationDecl *>()) {
+            dyn_cast_if_present<ClassTemplatePartialSpecializationDecl *>(
+                From)) {
       while (auto *NewCTPSD = CTPSD->getInstantiatedFromMember()) {
         if (NewCTPSD->isMemberSpecialization())
           break;
diff --git a/clang/lib/AST/DeclTemplate.cpp b/clang/lib/AST/DeclTemplate.cpp
index 2933ba7fb8a29..926b2b26dd381 100644
--- a/clang/lib/AST/DeclTemplate.cpp
+++ b/clang/lib/AST/DeclTemplate.cpp
@@ -1077,7 +1077,7 @@ ClassTemplateSpecializationDecl::getSourceRange() const {
 }
 
 void ClassTemplateSpecializationDecl::setExternKeywordLoc(SourceLocation Loc) {
-  auto *Info = ExplicitInfo.dyn_cast<ExplicitInstantiationInfo *>();
+  auto *Info = dyn_cast_if_present<ExplicitInstantiationInfo *>(ExplicitInfo);
   if (!Info) {
     // Don't allocate if the location is invalid.
     if (Loc.isInvalid())
@@ -1091,7 +1091,7 @@ void ClassTemplateSpecializationDecl::setExternKeywordLoc(SourceLocation Loc) {
 
 void ClassTemplateSpecializationDecl::setTemplateKeywordLoc(
     SourceLocation Loc) {
-  auto *Info = ExplicitInfo.dyn_cast<ExplicitInstantiationInfo *>();
+  auto *Info = dyn_cast_if_present<ExplicitInstantiationInfo *>(ExplicitInfo);
   if (!Info) {
     // Don't allocate if the location is invalid.
     if (Loc.isInvalid())
diff --git a/clang/lib/AST/TemplateName.cpp b/clang/lib/AST/TemplateName.cpp
index 7d6275caedc4f..3a1eb1ca12f45 100644
--- a/clang/lib/AST/TemplateName.cpp
+++ b/clang/lib/AST/TemplateName.cpp
@@ -182,7 +182,8 @@ TemplateDecl *TemplateName::getAsTemplateDecl(bool IgnoreDeduced) const {
            "Unexpected canonical DeducedTemplateName; Did you mean to use "
            "getTemplateDeclAndDefaultArgs instead?");
 
-  return cast_if_present<TemplateDecl>(Name.Storage.dyn_cast<Decl *>());
+  return cast_if_present<TemplateDecl>(
+      dyn_cast_if_present<Decl *>(Name.Storage));
 }
 
 std::pair<TemplateDecl *, DefaultArguments>
@@ -208,7 +209,7 @@ TemplateName::getTemplateDeclAndDefaultArgs() const {
 }
 
 std::optional<TemplateName> TemplateName::desugar(bool IgnoreDeduced) const {
-  if (Decl *D = Storage.dyn_cast<Decl *>()) {
+  if (Decl *D = dyn_cast_if_present<Decl *>(Storage)) {
     if (auto *USD = dyn_cast<UsingShadowDecl>(D))
       return TemplateName(USD->getTargetDecl());
     return std::nullopt;
@@ -242,7 +243,7 @@ AssumedTemplateStorage *TemplateName::getAsAssumedTemplateName() const {
 SubstTemplateTemplateParmStorage *
 TemplateName::getAsSubstTemplateTemplateParm() const {
   if (UncommonTemplateNameStorage *uncommon =
-          Storage.dyn_cast<UncommonTemplateNameStorage *>())
+          dyn_cast_if_present<UncommonTemplateNameStorage *>(Storage))
     return uncommon->getAsSubstTemplateTemplateParm();
 
   return nullptr;
@@ -258,7 +259,7 @@ TemplateName::getAsSubstTemplateTemplateParmPack() const {
 }
 
 QualifiedTemplateName *TemplateName::getAsQualifiedTemplateName() const {
-  return Storage.dyn_cast<QualifiedTemplateName *>();
+  return dyn_cast_if_present<QualifiedTemplateName *>(Storage);
 }
 
 DependentTemplateName *TemplateName::getAsDependentTemplateName() const {
@@ -276,7 +277,7 @@ UsingShadowDecl *TemplateName::getAsUsingShadowDecl() const {
 
 DeducedTemplateStorage *TemplateName::getAsDeducedTemplateName() const {
   if (UncommonTemplateNameStorage *Uncommon =
-          Storage.dyn_cast<UncommonTemplateNameStorage *>())
+          dyn_cast_if_present<UncommonTemplateNameStorage *>(Storage))
     return Uncommon->getAsDeducedTemplateName();
 
   return nullptr;
diff --git a/clang/lib/Frontend/SerializedDiagnosticPrinter.cpp b/clang/lib/Frontend/SerializedDiagnosticPrinter.cpp
index 0887b5a504f05..131334269aa75 100644
--- a/clang/lib/Frontend/SerializedDiagnosticPrinter.cpp
+++ b/clang/lib/Frontend/SerializedDiagnosticPrinter.cpp
@@ -650,7 +650,7 @@ void SDiagsWriter::EmitDiagnosticMessage(FullSourceLoc Loc, PresumedLoc PLoc,
   Record.push_back(getStableLevel(Level));
   AddLocToRecord(Loc, PLoc, Record);
 
-  if (const Diagnostic *Info = D.dyn_cast<const Diagnostic*>()) {
+  if (const Diagnostic *Info = dyn_cast_if_present<const Diagnostic *>(D)) {
     // Emit the category string lazily and get the category ID.
     unsigned DiagID = DiagnosticIDs::getCategoryNumberForDiag(Info->getID());
     Record.push_back(getEmitCategory(DiagID));
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index ad49eac66e98e..c3ff247a6316d 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -17700,9 +17700,11 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
             return PrevTagDecl;
 
           QualType EnumUnderlyingTy;
-          if (TypeSourceInfo *TI = EnumUnderlying.dyn_cast<TypeSourceInfo*>())
+          if (TypeSourceInfo *TI =
+                  dyn_cast_if_present<TypeSourceInfo *>(EnumUnderlying))
             EnumUnderlyingTy = TI->getType().getUnqualifiedType();
-          else if (const Type *T = EnumUnderlying.dyn_cast<const Type*>())
+          else if (const Type *T =
+                       dyn_cast_if_present<const Type *>(EnumUnderlying))
             EnumUnderlyingTy = QualType(T, 0);
 
           // All conflicts with previous declarations are recovered by
diff --git a/clang/tools/libclang/CIndexDiagnostic.cpp b/clang/tools/libclang/CIndexDiagnostic.cpp
index 34792d5bdfaaf..92271d9c37f86 100644
--- a/clang/tools/libclang/CIndexDiagnostic.cpp
+++ b/clang/tools/libclang/CIndexDiagnostic.cpp
@@ -92,7 +92,8 @@ class CXDiagnosticRenderer : public DiagnosticNoteRenderer {
   void beginDiagnostic(DiagOrStoredDiag D,
                        DiagnosticsEngine::Level Level) override {
 
-    const StoredDiagnostic *SD = D.dyn_cast<const StoredDiagnostic*>();
+    const StoredDiagnostic *SD =
+        dyn_cast_if_present<const StoredDiagnostic *>(D);
     if (!SD)
       return;