diff --git a/LanguageFeatures/Augmentation-libraries/merge_order_A01_t01.dart b/LanguageFeatures/Augmentation-libraries/merge_order_A01_t01.dart
new file mode 100644
index 0000000000..4324821b70
--- /dev/null
+++ b/LanguageFeatures/Augmentation-libraries/merge_order_A01_t01.dart
@@ -0,0 +1,24 @@
+// Copyright (c) 2024, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// @assertion The merge order is defined as a depth-first pre-order traversal
+/// of the import augment directives starting at the main library.
+///
+/// @description Checks the merge order of augment libraries
+/// @author sgrekhov22@gmail.com
+
+// SharedOptions=--enable-experiment=macros
+
+import '../../Utils/expect.dart';
+import augment 'merge_order_A01_t01_lib1.dart';
+import augment 'merge_order_A01_t01_lib3.dart';
+
+class A {}
+
+main() {
+  Expect.equals("Augmented A", A().foo());
+  Expect.equals("Augmented B", B().foo());
+  Expect.equals("Augmented C", C().foo());
+  Expect.equals("Augmented D", D().foo());
+}
diff --git a/LanguageFeatures/Augmentation-libraries/merge_order_A01_t01_lib1.dart b/LanguageFeatures/Augmentation-libraries/merge_order_A01_t01_lib1.dart
new file mode 100644
index 0000000000..043330b9f5
--- /dev/null
+++ b/LanguageFeatures/Augmentation-libraries/merge_order_A01_t01_lib1.dart
@@ -0,0 +1,20 @@
+// Copyright (c) 2024, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// @assertion The merge order is defined as a depth-first pre-order traversal
+/// of the import augment directives starting at the main library.
+///
+/// @description Checks the merge order of augment libraries
+/// @author sgrekhov22@gmail.com
+
+// SharedOptions=--enable-experiment=macros
+
+library augment 'merge_order_A01_t01.dart';
+
+import augment 'merge_order_A01_t01_lib2.dart';
+
+augment class A {
+  String foo() => "Augmented A";
+}
+class B {}
diff --git a/LanguageFeatures/Augmentation-libraries/merge_order_A01_t01_lib2.dart b/LanguageFeatures/Augmentation-libraries/merge_order_A01_t01_lib2.dart
new file mode 100644
index 0000000000..2cf8d1e1ae
--- /dev/null
+++ b/LanguageFeatures/Augmentation-libraries/merge_order_A01_t01_lib2.dart
@@ -0,0 +1,19 @@
+// Copyright (c) 2024, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// @assertion The merge order is defined as a depth-first pre-order traversal
+/// of the import augment directives starting at the main library.
+///
+/// @description Checks the merge order of augment libraries
+/// @author sgrekhov22@gmail.com
+
+// SharedOptions=--enable-experiment=macros
+
+library augment 'merge_order_A01_t01_lib1.dart';
+
+augment class B {
+  String foo() => "Augmented B";
+}
+class C {}
+class D {}
diff --git a/LanguageFeatures/Augmentation-libraries/merge_order_A01_t01_lib3.dart b/LanguageFeatures/Augmentation-libraries/merge_order_A01_t01_lib3.dart
new file mode 100644
index 0000000000..9ca7df9e54
--- /dev/null
+++ b/LanguageFeatures/Augmentation-libraries/merge_order_A01_t01_lib3.dart
@@ -0,0 +1,21 @@
+// Copyright (c) 2024, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// @assertion The merge order is defined as a depth-first pre-order traversal
+/// of the import augment directives starting at the main library.
+///
+/// @description Checks the merge order of augment libraries
+/// @author sgrekhov22@gmail.com
+
+// SharedOptions=--enable-experiment=macros
+
+library augment 'merge_order_A01_t01.dart';
+
+augment class C {
+  String foo() => "Augmented C";
+}
+
+augment class D {
+  String foo() => "Augmented D";
+}
diff --git a/LanguageFeatures/Augmentation-libraries/merge_order_A01_t02.dart b/LanguageFeatures/Augmentation-libraries/merge_order_A01_t02.dart
new file mode 100644
index 0000000000..cec1b4d26e
--- /dev/null
+++ b/LanguageFeatures/Augmentation-libraries/merge_order_A01_t02.dart
@@ -0,0 +1,27 @@
+// Copyright (c) 2024, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// @assertion The merge order is defined as a depth-first pre-order traversal
+/// of the import augment directives starting at the main library.
+///
+/// @description Checks that it is a compile-time error if an augmenting
+/// declaration appears in a library before the library where the original
+/// declaration occurs, according to merge order
+/// @author sgrekhov22@gmail.com
+
+// SharedOptions=--enable-experiment=macros
+
+import augment 'merge_order_A01_t02_lib1.dart';
+import augment 'merge_order_A01_t02_lib3.dart';
+
+augment class A {}
+//            ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+main() {
+  print(A);
+  print(B);
+  print(C);
+}
diff --git a/LanguageFeatures/Augmentation-libraries/merge_order_A01_t02_lib1.dart b/LanguageFeatures/Augmentation-libraries/merge_order_A01_t02_lib1.dart
new file mode 100644
index 0000000000..7992b55cd9
--- /dev/null
+++ b/LanguageFeatures/Augmentation-libraries/merge_order_A01_t02_lib1.dart
@@ -0,0 +1,24 @@
+// Copyright (c) 2024, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// @assertion The merge order is defined as a depth-first pre-order traversal
+/// of the import augment directives starting at the main library.
+///
+/// @description Checks that it is a compile-time error if an augmenting
+/// declaration appears in a library before the library where the original
+/// declaration occurs, according to merge order
+/// @author sgrekhov22@gmail.com
+
+// SharedOptions=--enable-experiment=macros
+
+library augment 'merge_order_A01_t02.dart';
+
+import augment 'merge_order_A01_t02_lib2.dart';
+
+class A {
+}
+augment class B {}
+//            ^
+// [analyzer] unspecified
+// [cfe] unspecified
diff --git a/LanguageFeatures/Augmentation-libraries/merge_order_A01_t02_lib2.dart b/LanguageFeatures/Augmentation-libraries/merge_order_A01_t02_lib2.dart
new file mode 100644
index 0000000000..c81721de83
--- /dev/null
+++ b/LanguageFeatures/Augmentation-libraries/merge_order_A01_t02_lib2.dart
@@ -0,0 +1,22 @@
+// Copyright (c) 2024, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// @assertion The merge order is defined as a depth-first pre-order traversal
+/// of the import augment directives starting at the main library.
+///
+/// @description Checks that it is a compile-time error if an augmenting
+/// declaration appears in a library before the library where the original
+/// declaration occurs, according to merge order
+/// @author sgrekhov22@gmail.com
+
+// SharedOptions=--enable-experiment=macros
+
+library augment 'merge_order_A01_t02_lib1.dart';
+
+class B {}
+
+augment class C {}
+//            ^
+// [analyzer] unspecified
+// [cfe] unspecified
diff --git a/LanguageFeatures/Augmentation-libraries/merge_order_A01_t02_lib3.dart b/LanguageFeatures/Augmentation-libraries/merge_order_A01_t02_lib3.dart
new file mode 100644
index 0000000000..acf0fee1a1
--- /dev/null
+++ b/LanguageFeatures/Augmentation-libraries/merge_order_A01_t02_lib3.dart
@@ -0,0 +1,17 @@
+// Copyright (c) 2024, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// @assertion The merge order is defined as a depth-first pre-order traversal
+/// of the import augment directives starting at the main library.
+///
+/// @description Checks that it is a compile-time error if an augmenting
+/// declaration appears in a library before the library where the original
+/// declaration occurs, according to merge order
+/// @author sgrekhov22@gmail.com
+
+// SharedOptions=--enable-experiment=macros
+
+library augment 'merge_order_A01_t02.dart';
+
+class C {}