diff --git a/ext/standard/array.c b/ext/standard/array.c
index 6252b61d2042a..1343f262e1b83 100644
--- a/ext/standard/array.c
+++ b/ext/standard/array.c
@@ -4559,6 +4559,43 @@ PHP_FUNCTION(array_unique)
 		return;
 	}
 
+	if (sort_type == PHP_ARRAY_UNIQUE_UNSORTED) {
+		zend_long input_num_key;
+		zend_string *input_str_key;
+		zval *input_val;
+
+		array_init(return_value);
+		HashTable *result_ht = Z_ARR_P(return_value);
+
+		ZEND_HASH_FOREACH_KEY_VAL(Z_ARRVAL_P(array), input_num_key, input_str_key, input_val) {
+			zval *input_val_deref = input_val;
+			ZVAL_DEREF(input_val_deref);
+
+			zval *result_val;
+			ZEND_HASH_FOREACH_VAL(result_ht, result_val) {
+				ZVAL_DEREF(result_val);
+				if (fast_is_identical_function(input_val_deref, result_val)) {
+					goto skip_unsorted;
+				}
+			} ZEND_HASH_FOREACH_END();
+
+			if (UNEXPECTED(Z_ISREF_P(input_val) && Z_REFCOUNT_P(input_val) == 1)) {
+				ZVAL_DEREF(input_val);
+			}
+			Z_TRY_ADDREF_P(input_val);
+
+			if (input_str_key) {
+				zend_hash_add_new(Z_ARRVAL_P(return_value), input_str_key, input_val);
+			} else {
+				zend_hash_index_add_new(Z_ARRVAL_P(return_value), input_num_key, input_val);
+			}
+
+skip_unsorted:;
+		} ZEND_HASH_FOREACH_END();
+
+		return;
+	}
+
 	cmp = php_get_data_compare_func_unstable(sort_type, 0);
 
 	RETVAL_ARR(zend_array_dup(Z_ARRVAL_P(array)));
diff --git a/ext/standard/basic_functions.stub.php b/ext/standard/basic_functions.stub.php
index ab56a8c0e8fbb..9737928ba9035 100755
--- a/ext/standard/basic_functions.stub.php
+++ b/ext/standard/basic_functions.stub.php
@@ -87,6 +87,12 @@
  */
 const SORT_FLAG_CASE = UNKNOWN;
 
+/**
+ * @var int
+ * @cvalue PHP_ARRAY_UNIQUE_UNSORTED
+ */
+const ARRAY_UNIQUE_UNSORTED = UNKNOWN;
+
 /**
  * @var int
  * @cvalue PHP_CASE_LOWER
diff --git a/ext/standard/basic_functions_arginfo.h b/ext/standard/basic_functions_arginfo.h
index 077f9876df7c2..1811535a9ce7e 100644
--- a/ext/standard/basic_functions_arginfo.h
+++ b/ext/standard/basic_functions_arginfo.h
@@ -1,5 +1,5 @@
 /* This is a generated file, edit the .stub.php file instead.
- * Stub hash: 39d455982dfdea9d0b9b646bc207b05f7108d1b2 */
+ * Stub hash: e50a074c7bef1f26a4a1c643af5bfce641cb6a68 */
 
 ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO_EX(arginfo_set_time_limit, 0, 1, _IS_BOOL, 0)
 	ZEND_ARG_TYPE_INFO(0, seconds, IS_LONG, 0)
@@ -3499,6 +3499,7 @@ static void register_basic_functions_symbols(int module_number)
 	REGISTER_LONG_CONSTANT("SORT_LOCALE_STRING", PHP_SORT_LOCALE_STRING, CONST_PERSISTENT);
 	REGISTER_LONG_CONSTANT("SORT_NATURAL", PHP_SORT_NATURAL, CONST_PERSISTENT);
 	REGISTER_LONG_CONSTANT("SORT_FLAG_CASE", PHP_SORT_FLAG_CASE, CONST_PERSISTENT);
+	REGISTER_LONG_CONSTANT("ARRAY_UNIQUE_UNSORTED", PHP_ARRAY_UNIQUE_UNSORTED, CONST_PERSISTENT);
 	REGISTER_LONG_CONSTANT("CASE_LOWER", PHP_CASE_LOWER, CONST_PERSISTENT);
 	REGISTER_LONG_CONSTANT("CASE_UPPER", PHP_CASE_UPPER, CONST_PERSISTENT);
 	REGISTER_LONG_CONSTANT("COUNT_NORMAL", PHP_COUNT_NORMAL, CONST_PERSISTENT);
diff --git a/ext/standard/php_array.h b/ext/standard/php_array.h
index 5d42a22f42040..a82af809f038b 100644
--- a/ext/standard/php_array.h
+++ b/ext/standard/php_array.h
@@ -55,6 +55,10 @@ PHPAPI bool php_array_pick_keys(const php_random_algo *algo, php_random_status *
 #define PHP_SORT_LOCALE_STRING      5
 #define PHP_SORT_NATURAL            6
 #define PHP_SORT_FLAG_CASE          8
+//#define PHP_SORT_DONT_USE         9
+
+// Must not clash with PHP_SORT_ constants
+#define PHP_ARRAY_UNIQUE_UNSORTED   9
 
 #define PHP_COUNT_NORMAL      0
 #define PHP_COUNT_RECURSIVE   1
diff --git a/ext/standard/tests/array/array_unique_unsorted.phpt b/ext/standard/tests/array/array_unique_unsorted.phpt
new file mode 100755
index 0000000000000..76e9978292cb3
--- /dev/null
+++ b/ext/standard/tests/array/array_unique_unsorted.phpt
@@ -0,0 +1,83 @@
+--TEST--
+array_unique() with ARRAY_UNIQUE_UNSORTED
+--FILE--
+<?php
+
+enum Foo {
+    case Bar;
+    case Baz;
+}
+
+$bar = Foo::Bar;
+$bar2 = Foo::Bar;
+
+var_dump(array_unique([
+    Foo::Bar,
+    Foo::Baz,
+    Foo::Baz,
+    Foo::Bar,
+], ARRAY_UNIQUE_UNSORTED));
+
+var_dump(array_unique([
+    Foo::Bar,
+    Foo::Bar,
+    Foo::Baz,
+], ARRAY_UNIQUE_UNSORTED));
+
+var_dump(array_unique([
+    'a' => Foo::Bar,
+    'b' => Foo::Baz,
+    'c' => Foo::Bar,
+], ARRAY_UNIQUE_UNSORTED));
+
+var_dump(array_unique([
+    &$bar,
+    Foo::Bar,
+    &$bar2,
+    Foo::Baz,
+], ARRAY_UNIQUE_UNSORTED));
+
+$value2 = "hello";
+$value3 = 0;
+$value4 = &$value2;
+var_dump(array_unique([
+    0,
+    &$value4,
+    &$value2,
+    "hello",
+    &$value3,
+    $value4
+], ARRAY_UNIQUE_UNSORTED));
+
+?>
+--EXPECT--
+array(2) {
+  [0]=>
+  enum(Foo::Bar)
+  [1]=>
+  enum(Foo::Baz)
+}
+array(2) {
+  [0]=>
+  enum(Foo::Bar)
+  [2]=>
+  enum(Foo::Baz)
+}
+array(2) {
+  ["a"]=>
+  enum(Foo::Bar)
+  ["b"]=>
+  enum(Foo::Baz)
+}
+array(2) {
+  [0]=>
+  &enum(Foo::Bar)
+  [3]=>
+  enum(Foo::Baz)
+}
+array(2) {
+  [0]=>
+  int(0)
+  [1]=>
+  &string(5) "hello"
+}