diff --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td
--- a/clang/include/clang/Basic/Attr.td
+++ b/clang/include/clang/Basic/Attr.td
@@ -1864,6 +1864,13 @@
   let Documentation = [Undocumented];
 }
 
+def NSErrorDomain : InheritableAttr {
+  let Spellings = [GNU<"ns_error_domain">];
+  let Subjects = SubjectList<[Enum], ErrorDiag>;
+  let Args = [IdentifierArgument<"ErrorDomain">];
+  let Documentation = [NSErrorDomainDocs];
+}
+
 def NSReturnsRetained : DeclOrTypeAttr {
   let Spellings = [Clang<"ns_returns_retained">];
 //  let Subjects = SubjectList<[ObjCMethod, ObjCProperty, Function]>;
diff --git a/clang/include/clang/Basic/AttrDocs.td b/clang/include/clang/Basic/AttrDocs.td
--- a/clang/include/clang/Basic/AttrDocs.td
+++ b/clang/include/clang/Basic/AttrDocs.td
@@ -3313,6 +3313,38 @@
   }];
 }
 
+def NSErrorDomainDocs : Documentation {
+  let Category = DocCatDecl;
+  let Content = [{
+In Cocoa frameworks in Objective-C, one can group related error codes in enums
+and categorize these enums with error domains.
+
+The ``ns_error_domain`` attribute indicates a global ``NSString`` constant
+representing the error domain that an error code belongs to. For pointer
+uniqueness and code size this is a constant symbol, not a literal.
+
+The domain and error code need to be used together. The ``ns_error_domain``
+attribute links error codes to their domain at the source level.
+
+This metadata is useful for documentation purposes, for static analysis, and for
+improving interoperability between Objective-C and Swift. It is not used for
+code generation in Objective-C.
+
+For example:
+
+  .. code-block:: objc
+
+    #define NS_ERROR_ENUM(_type, _name, _domain)  \
+      enum _name : _type _name; enum __attribute__((ns_error_domain(_domain))) _name : _type
+
+    extern NSString *const MyErrorDomain;
+    typedef NS_ERROR_ENUM(unsigned char, MyErrorEnum, MyErrorDomain) {
+      MyErrFirst,
+      MyErrSecond,
+    };
+  }];
+}
+
 def OMPDeclareSimdDocs : Documentation {
   let Category = DocCatFunction;
   let Heading = "#pragma omp declare simd";
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -9458,6 +9458,9 @@
 def err_nsreturns_retained_attribute_mismatch : Error<
   "overriding method has mismatched ns_returns_%select{not_retained|retained}0"
   " attributes">;
+def err_nserrordomain_invalid_decl : Error<
+  "domain argument %0 does not refer to global constant">;
+
 def warn_nsconsumed_attribute_mismatch : Warning<
   err_nsconsumed_attribute_mismatch.Text>, InGroup<NSConsumedMismatch>;
 def warn_nsreturns_retained_attribute_mismatch : Warning<
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -5322,6 +5322,35 @@
   D->addAttr(::new (S.Context) ObjCRequiresSuperAttr(S.Context, Attrs));
 }
 
+static void handleNSErrorDomain(Sema &S, Decl *D, const ParsedAttr &AL) {
+  IdentifierLoc *IdentLoc = AL.isArgIdent(0) ? AL.getArgAsIdent(0) : nullptr;
+  if (!IdentLoc || !IdentLoc->Ident) {
+    // Try to locate the argument directly
+    SourceLocation Loc = AL.getLoc();
+    if (const Expr *E = AL.getArgAsExpr(0))
+      Loc = E->getBeginLoc();
+
+    S.Diag(Loc, diag::err_attribute_argument_n_type)
+        << AL << 1 << AANT_ArgumentIdentifier;
+
+    return;
+  }
+
+  // Verify that the identifier is a valid decl in the C decl namespace
+  LookupResult lookupResult(S, DeclarationName(IdentLoc->Ident),
+                            SourceLocation(),
+                            Sema::LookupNameKind::LookupOrdinaryName);
+  if (!S.LookupName(lookupResult, S.TUScope) ||
+      !lookupResult.getAsSingle<VarDecl>()) {
+    S.Diag(IdentLoc->Loc, diag::err_nserrordomain_invalid_decl)
+        << IdentLoc->Ident;
+    return;
+  }
+
+  D->addAttr(::new (S.Context)
+                 NSErrorDomainAttr(S.Context, AL, IdentLoc->Ident));
+}
+
 static void handleObjCBridgeAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
   IdentifierLoc *Parm = AL.isArgIdent(0) ? AL.getArgAsIdent(0) : nullptr;
 
@@ -7093,6 +7122,9 @@
   case ParsedAttr::AT_ObjCBoxable:
     handleObjCBoxable(S, D, AL);
     break;
+  case ParsedAttr::AT_NSErrorDomain:
+    handleNSErrorDomain(S, D, AL);
+    break;
   case ParsedAttr::AT_CFAuditedTransfer:
     handleSimpleAttributeWithExclusions<CFAuditedTransferAttr,
                                         CFUnknownTransferAttr>(S, D, AL);
diff --git a/clang/test/Misc/pragma-attribute-supported-attributes-list.test b/clang/test/Misc/pragma-attribute-supported-attributes-list.test
--- a/clang/test/Misc/pragma-attribute-supported-attributes-list.test
+++ b/clang/test/Misc/pragma-attribute-supported-attributes-list.test
@@ -80,6 +80,7 @@
 // CHECK-NEXT: MipsShortCall (SubjectMatchRule_function)
 // CHECK-NEXT: NSConsumed (SubjectMatchRule_variable_is_parameter)
 // CHECK-NEXT: NSConsumesSelf (SubjectMatchRule_objc_method)
+// CHECK-NEXT: NSErrorDomain (SubjectMatchRule_enum)
 // CHECK-NEXT: Naked (SubjectMatchRule_function)
 // CHECK-NEXT: NoBuiltin (SubjectMatchRule_function)
 // CHECK-NEXT: NoCommon (SubjectMatchRule_variable)
diff --git a/clang/test/Sema/ns_error_enum.m b/clang/test/Sema/ns_error_enum.m
new file mode 100644
--- /dev/null
+++ b/clang/test/Sema/ns_error_enum.m
@@ -0,0 +1,54 @@
+// RUN: %clang_cc1 -verify %s -x objective-c
+// RUN: %clang_cc1 -verify %s -x objective-c++
+
+
+#define CF_ENUM(_type, _name) enum _name : _type _name; enum _name : _type
+#define NS_ENUM(_type, _name) CF_ENUM(_type, _name)
+
+#define NS_ERROR_ENUM(_type, _name, _domain)  \
+  enum _name : _type _name; enum __attribute__((ns_error_domain(_domain))) _name : _type
+
+typedef NS_ENUM(unsigned, MyEnum) {
+  MyFirst,
+  MySecond,
+};
+
+typedef NS_ENUM(invalidType, MyInvalidEnum) {
+// expected-error@-1{{unknown type name 'invalidType'}}
+// expected-error@-2{{unknown type name 'invalidType'}}
+  MyFirstInvalid,
+  MySecondInvalid,
+};
+
+@interface NSString
+@end
+
+extern NSString *const MyErrorDomain;
+typedef NS_ERROR_ENUM(unsigned char, MyErrorEnum, MyErrorDomain) {
+	MyErrFirst,
+	MyErrSecond,
+};
+struct __attribute__((ns_error_domain(MyErrorDomain))) MyStructWithErrorDomain {};
+// expected-error@-1{{'ns_error_domain' attribute only applies to enums}}
+
+int __attribute__((ns_error_domain(MyErrorDomain))) NotTagDecl;
+  // expected-error@-1{{'ns_error_domain' attribute only applies to enums}}
+
+enum __attribute__((ns_error_domain())) NoArg { NoArgError };
+// expected-error@-1{{'ns_error_domain' attribute takes one argument}}
+
+enum __attribute__((ns_error_domain(MyErrorDomain, MyErrorDomain))) TwoArgs { TwoArgsError };
+// expected-error@-1{{'ns_error_domain' attribute takes one argument}}
+
+typedef NS_ERROR_ENUM(unsigned char, MyErrorEnumInvalid, InvalidDomain) {
+	// expected-error@-1{{domain argument 'InvalidDomain' does not refer to global constant}}
+	MyErrFirstInvalid,
+	MyErrSecondInvalid,
+};
+
+typedef NS_ERROR_ENUM(unsigned char, MyErrorEnumInvalid, "domain-string");
+  // expected-error@-1{{'ns_error_domain' attribute requires parameter 1 to be an identifier}}
+
+void foo() {}
+typedef NS_ERROR_ENUM(unsigned char, MyErrorEnumInvalidFunction, foo);
+  // expected-error@-1{{domain argument 'foo' does not refer to global constant}}