Index: include/clang/AST/ASTImporter.h
===================================================================
--- include/clang/AST/ASTImporter.h
+++ include/clang/AST/ASTImporter.h
@@ -166,30 +166,41 @@
     }
 
     /// Import the given type from the "from" context into the "to"
-    /// context.
+    /// context. A null type is imported as a null type (no error).
     ///
-    /// \returns the equivalent type in the "to" context, or a NULL type if
-    /// an error occurred.
+    /// \returns The equivalent type in the "to" context, or the import error.
+    llvm::Expected<QualType> Import_New(QualType FromT);
+    // FIXME: Remove this version.
     QualType Import(QualType FromT);
 
     /// Import the given type source information from the
     /// "from" context into the "to" context.
     ///
-    /// \returns the equivalent type source information in the "to"
-    /// context, or NULL if an error occurred.
+    /// \returns The equivalent type source information in the "to"
+    /// context, or the import error.
+    llvm::Expected<TypeSourceInfo *> Import_New(TypeSourceInfo *FromTSI);
+    // FIXME: Remove this version.
     TypeSourceInfo *Import(TypeSourceInfo *FromTSI);
 
     /// Import the given attribute from the "from" context into the
     /// "to" context.
     ///
-    /// \returns the equivalent attribute in the "to" context.
+    /// \returns The equivalent attribute in the "to" context, or the import
+    /// error.
+    llvm::Expected<Attr *> Import_New(const Attr *FromAttr);
+    // FIXME: Remove this version.
     Attr *Import(const Attr *FromAttr);
 
     /// Import the given declaration from the "from" context into the
     /// "to" context.
     ///
-    /// \returns the equivalent declaration in the "to" context, or a NULL type
-    /// if an error occurred.
+    /// \returns The equivalent declaration in the "to" context, or the import
+    /// error.
+    llvm::Expected<Decl *> Import_New(Decl *FromD);
+    llvm::Expected<Decl *> Import_New(const Decl *FromD) {
+      return Import_New(const_cast<Decl *>(FromD));
+    }
+    // FIXME: Remove this version.
     Decl *Import(Decl *FromD);
     Decl *Import(const Decl *FromD) {
       return Import(const_cast<Decl *>(FromD));
@@ -210,87 +221,117 @@
     /// Import the given expression from the "from" context into the
     /// "to" context.
     ///
-    /// \returns the equivalent expression in the "to" context, or NULL if
-    /// an error occurred.
+    /// \returns The equivalent expression in the "to" context, or the import
+    /// error.
+    llvm::Expected<Expr *> Import_New(Expr *FromE);
+    // FIXME: Remove this version.
     Expr *Import(Expr *FromE);
 
     /// Import the given statement from the "from" context into the
     /// "to" context.
     ///
-    /// \returns the equivalent statement in the "to" context, or NULL if
-    /// an error occurred.
+    /// \returns The equivalent statement in the "to" context, or the import
+    /// error.
+    llvm::Expected<Stmt *> Import_New(Stmt *FromS);
+    // FIXME: Remove this version.
     Stmt *Import(Stmt *FromS);
 
     /// Import the given nested-name-specifier from the "from"
     /// context into the "to" context.
     ///
-    /// \returns the equivalent nested-name-specifier in the "to"
-    /// context, or NULL if an error occurred.
+    /// \returns The equivalent nested-name-specifier in the "to"
+    /// context, or the import error.
+    llvm::Expected<NestedNameSpecifier *>
+    Import_New(NestedNameSpecifier *FromNNS);
+    // FIXME: Remove this version.
     NestedNameSpecifier *Import(NestedNameSpecifier *FromNNS);
 
-    /// Import the given nested-name-specifier from the "from"
+    /// Import the given nested-name-specifier-loc from the "from"
     /// context into the "to" context.
     ///
-    /// \returns the equivalent nested-name-specifier in the "to"
-    /// context.
+    /// \returns The equivalent nested-name-specifier-loc in the "to"
+    /// context, or the import error.
+    llvm::Expected<NestedNameSpecifierLoc>
+    Import_New(NestedNameSpecifierLoc FromNNS);
+    // FIXME: Remove this version.
     NestedNameSpecifierLoc Import(NestedNameSpecifierLoc FromNNS);
 
-    /// Import the goven template name from the "from" context into the
-    /// "to" context.
+    /// Import the given template name from the "from" context into the
+    /// "to" context, or the import error.
+    llvm::Expected<TemplateName> Import_New(TemplateName From);
+    // FIXME: Remove this version.
     TemplateName Import(TemplateName From);
 
     /// Import the given source location from the "from" context into
     /// the "to" context.
     ///
-    /// \returns the equivalent source location in the "to" context, or an
-    /// invalid source location if an error occurred.
+    /// \returns The equivalent source location in the "to" context, or the
+    /// import error.
+    llvm::Expected<SourceLocation> Import_New(SourceLocation FromLoc);
+    // FIXME: Remove this version.
     SourceLocation Import(SourceLocation FromLoc);
 
     /// Import the given source range from the "from" context into
     /// the "to" context.
     ///
-    /// \returns the equivalent source range in the "to" context, or an
-    /// invalid source location if an error occurred.
+    /// \returns The equivalent source range in the "to" context, or the import
+    /// error.
+    llvm::Expected<SourceRange> Import_New(SourceRange FromRange);
+    // FIXME: Remove this version.
     SourceRange Import(SourceRange FromRange);
 
     /// Import the given declaration name from the "from"
     /// context into the "to" context.
     ///
-    /// \returns the equivalent declaration name in the "to" context,
-    /// or an empty declaration name if an error occurred.
+    /// \returns The equivalent declaration name in the "to" context, or the
+    /// import error.
+    llvm::Expected<DeclarationName> Import_New(DeclarationName FromName);
+    // FIXME: Remove this version.
     DeclarationName Import(DeclarationName FromName);
 
     /// Import the given identifier from the "from" context
     /// into the "to" context.
     ///
-    /// \returns the equivalent identifier in the "to" context. Note: It
+    /// \returns The equivalent identifier in the "to" context. Note: It
     /// returns nullptr only if the FromId was nullptr.
     IdentifierInfo *Import(const IdentifierInfo *FromId);
 
     /// Import the given Objective-C selector from the "from"
     /// context into the "to" context.
     ///
-    /// \returns the equivalent selector in the "to" context.
+    /// \returns The equivalent selector in the "to" context, or the import
+    /// error.
+    llvm::Expected<Selector> Import_New(Selector FromSel);
+    // FIXME: Remove this version.
     Selector Import(Selector FromSel);
 
     /// Import the given file ID from the "from" context into the
     /// "to" context.
     ///
-    /// \returns the equivalent file ID in the source manager of the "to"
-    /// context.
+    /// \returns The equivalent file ID in the source manager of the "to"
+    /// context, or the import error.
+    llvm::Expected<FileID> Import_New(FileID);
+    // FIXME: Remove this version.
     FileID Import(FileID);
 
     /// Import the given C++ constructor initializer from the "from"
     /// context into the "to" context.
     ///
-    /// \returns the equivalent initializer in the "to" context.
+    /// \returns The equivalent initializer in the "to" context, or the import
+    /// error.
+    llvm::Expected<CXXCtorInitializer *>
+    Import_New(CXXCtorInitializer *FromInit);
+    // FIXME: Remove this version.
     CXXCtorInitializer *Import(CXXCtorInitializer *FromInit);
 
     /// Import the given CXXBaseSpecifier from the "from" context into
     /// the "to" context.
     ///
-    /// \returns the equivalent CXXBaseSpecifier in the source manager of the
-    /// "to" context.
+    /// \returns The equivalent CXXBaseSpecifier in the source manager of the
+    /// "to" context, or the import error.
+    llvm::Expected<CXXBaseSpecifier *>
+    Import_New(const CXXBaseSpecifier *FromSpec);
+    // FIXME: Remove this version.
     CXXBaseSpecifier *Import(const CXXBaseSpecifier *FromSpec);
 
     /// Import the definition of the given declaration, including all of
Index: lib/AST/ASTImporter.cpp
===================================================================
--- lib/AST/ASTImporter.cpp
+++ lib/AST/ASTImporter.cpp
@@ -7656,6 +7656,12 @@
 
 ASTImporter::~ASTImporter() = default;
 
+Expected<QualType> ASTImporter::Import_New(QualType FromT) {
+  QualType ToT = Import(FromT);
+  if (ToT.isNull() && !FromT.isNull())
+    return make_error<ImportError>();
+  return ToT;
+}
 QualType ASTImporter::Import(QualType FromT) {
   if (FromT.isNull())
     return {};
@@ -7682,6 +7688,12 @@
   return ToContext.getQualifiedType(*ToTOrErr, FromT.getLocalQualifiers());
 }
 
+Expected<TypeSourceInfo *> ASTImporter::Import_New(TypeSourceInfo *FromTSI) {
+  TypeSourceInfo *ToTSI = Import(FromTSI);
+  if (!ToTSI && FromTSI)
+    return llvm::make_error<ImportError>();
+  return ToTSI;
+}
 TypeSourceInfo *ASTImporter::Import(TypeSourceInfo *FromTSI) {
   if (!FromTSI)
     return FromTSI;
@@ -7696,8 +7708,12 @@
       T, Import(FromTSI->getTypeLoc().getBeginLoc()));
 }
 
+Expected<Attr *> ASTImporter::Import_New(const Attr *FromAttr) {
+  return Import(FromAttr);
+}
 Attr *ASTImporter::Import(const Attr *FromAttr) {
   Attr *ToAttr = FromAttr->clone(ToContext);
+  // NOTE: Import of SourceRange may fail.
   ToAttr->setRange(Import(FromAttr->getRange()));
   return ToAttr;
 }
@@ -7715,6 +7731,12 @@
   }
 }
 
+Expected<Decl *> ASTImporter::Import_New(Decl *FromD) {
+  Decl *ToD = Import(FromD);
+  if (!ToD && FromD)
+    return llvm::make_error<ImportError>();
+  return ToD;
+}
 Decl *ASTImporter::Import(Decl *FromD) {
   if (!FromD)
     return nullptr;
@@ -7803,6 +7825,12 @@
   return ToDC;
 }
 
+Expected<Expr *> ASTImporter::Import_New(Expr *FromE) {
+  Expr *ToE = Import(FromE);
+  if (!ToE && FromE)
+    return llvm::make_error<ImportError>();
+  return ToE;
+}
 Expr *ASTImporter::Import(Expr *FromE) {
   if (!FromE)
     return nullptr;
@@ -7810,6 +7838,12 @@
   return cast_or_null<Expr>(Import(cast<Stmt>(FromE)));
 }
 
+Expected<Stmt *> ASTImporter::Import_New(Stmt *FromS) {
+  Stmt *ToS = Import(FromS);
+  if (!ToS && FromS)
+    return llvm::make_error<ImportError>();
+  return ToS;
+}
 Stmt *ASTImporter::Import(Stmt *FromS) {
   if (!FromS)
     return nullptr;
@@ -7845,6 +7879,13 @@
   return *ToSOrErr;
 }
 
+Expected<NestedNameSpecifier *>
+ASTImporter::Import_New(NestedNameSpecifier *FromNNS) {
+  NestedNameSpecifier *ToNNS = Import(FromNNS);
+  if (!ToNNS && FromNNS)
+    return llvm::make_error<ImportError>();
+  return ToNNS;
+}
 NestedNameSpecifier *ASTImporter::Import(NestedNameSpecifier *FromNNS) {
   if (!FromNNS)
     return nullptr;
@@ -7898,6 +7939,11 @@
   llvm_unreachable("Invalid nested name specifier kind");
 }
 
+Expected<NestedNameSpecifierLoc>
+ASTImporter::Import_New(NestedNameSpecifierLoc FromNNS) {
+  NestedNameSpecifierLoc ToNNS = Import(FromNNS);
+  return ToNNS;
+}
 NestedNameSpecifierLoc ASTImporter::Import(NestedNameSpecifierLoc FromNNS) {
   // Copied from NestedNameSpecifier mostly.
   SmallVector<NestedNameSpecifierLoc , 8> NestedNames;
@@ -7969,6 +8015,12 @@
   return Builder.getWithLocInContext(getToContext());
 }
 
+Expected<TemplateName> ASTImporter::Import_New(TemplateName From) {
+  TemplateName To = Import(From);
+  if (To.isNull() && !From.isNull())
+    return llvm::make_error<ImportError>();
+  return To;
+}
 TemplateName ASTImporter::Import(TemplateName From) {
   switch (From.getKind()) {
   case TemplateName::Template:
@@ -8059,6 +8111,12 @@
   llvm_unreachable("Invalid template name kind");
 }
 
+Expected<SourceLocation> ASTImporter::Import_New(SourceLocation FromLoc) {
+  SourceLocation ToLoc = Import(FromLoc);
+  if (ToLoc.isInvalid() && !FromLoc.isInvalid())
+    return llvm::make_error<ImportError>();
+  return ToLoc;
+}
 SourceLocation ASTImporter::Import(SourceLocation FromLoc) {
   if (FromLoc.isInvalid())
     return {};
@@ -8073,10 +8131,20 @@
   return ToSM.getComposedLoc(ToFileID, Decomposed.second);
 }
 
+Expected<SourceRange> ASTImporter::Import_New(SourceRange FromRange) {
+  SourceRange ToRange = Import(FromRange);
+  return ToRange;
+}
 SourceRange ASTImporter::Import(SourceRange FromRange) {
   return SourceRange(Import(FromRange.getBegin()), Import(FromRange.getEnd()));
 }
 
+Expected<FileID> ASTImporter::Import_New(FileID FromID) {
+  FileID ToID = Import(FromID);
+  if (ToID.isInvalid() && FromID.isValid())
+    return llvm::make_error<ImportError>();
+  return ToID;
+}
 FileID ASTImporter::Import(FileID FromID) {
   llvm::DenseMap<FileID, FileID>::iterator Pos = ImportedFileIDs.find(FromID);
   if (Pos != ImportedFileIDs.end())
@@ -8134,6 +8202,13 @@
   return ToID;
 }
 
+Expected<CXXCtorInitializer *>
+ASTImporter::Import_New(CXXCtorInitializer *From) {
+  CXXCtorInitializer *To = Import(From);
+  if (!To && From)
+    return llvm::make_error<ImportError>();
+  return To;
+}
 CXXCtorInitializer *ASTImporter::Import(CXXCtorInitializer *From) {
   Expr *ToExpr = Import(From->getInit());
   if (!ToExpr && From->getInit())
@@ -8179,6 +8254,13 @@
   }
 }
 
+Expected<CXXBaseSpecifier *>
+ASTImporter::Import_New(const CXXBaseSpecifier *From) {
+  CXXBaseSpecifier *To = Import(From);
+  if (!To && From)
+    return llvm::make_error<ImportError>();
+  return To;
+}
 CXXBaseSpecifier *ASTImporter::Import(const CXXBaseSpecifier *BaseSpec) {
   auto Pos = ImportedCXXBaseSpecifiers.find(BaseSpec);
   if (Pos != ImportedCXXBaseSpecifiers.end())
@@ -8244,6 +8326,12 @@
   llvm::consumeError(std::move(Err));
 }
 
+Expected<DeclarationName> ASTImporter::Import_New(DeclarationName FromName) {
+  DeclarationName ToName = Import(FromName);
+  if (!ToName && FromName)
+    return llvm::make_error<ImportError>();
+  return ToName;
+}
 DeclarationName ASTImporter::Import(DeclarationName FromName) {
   if (!FromName)
     return {};
@@ -8320,6 +8408,12 @@
   return ToId;
 }
 
+Expected<Selector> ASTImporter::Import_New(Selector FromSel) {
+  Selector ToSel = Import(FromSel);
+  if (ToSel.isNull() && !FromSel.isNull())
+    return llvm::make_error<ImportError>();
+  return ToSel;
+}
 Selector ASTImporter::Import(Selector FromSel) {
   if (FromSel.isNull())
     return {};