diff --git a/lib/VM/EnumCaseSupport.php b/lib/VM/EnumCaseSupport.php
index 32dd5f344f1..5227b19d96f 100644
--- a/lib/VM/EnumCaseSupport.php
+++ b/lib/VM/EnumCaseSupport.php
@@ -306,9 +306,10 @@ public static function compareEnumCaseEntrySpaceship(EnumCaseEntry $left, EnumCa
     }
 
     /**
-     * Transitive ordering for sort()/asort() on enum case arrays (#5546, php-src array.c php_array_compare_transitive).
+     * Transitive ordering for sort()/asort() on enum case arrays (#5546, #5691, php-src array.c).
      *
-     * Backed enums: backing scalar spaceship. Unit enums: object handle (spl_object_id order).
+     * php-src SORT_REGULAR uses stable object-handle order for enum zvals, not backing scalars
+     * (php_array_data_compare_unstable_i / php_array_compare_transitive, PR #20517).
      */
     public static function compareEnumCasesForSort(Variable $left, Variable $right): int
     {
@@ -323,12 +324,6 @@ public static function compareEnumCasesForSort(Variable $left, Variable $right):
         if ($leftName === $rightName) {
             return 0;
         }
-        if (null !== $leftClass->backedType) {
-            return Variable::spaceshipCompare(
-                self::backingValueForMinMax($left),
-                self::backingValueForMinMax($right)
-            );
-        }
 
         return self::objectIdForEnumSort($left) <=> self::objectIdForEnumSort($right);
     }
diff --git a/test/compliance/cases/stdlib/sort_enum_cases.phpt b/test/compliance/cases/stdlib/sort_enum_cases.phpt
index c068efa098f..51fee157148 100644
--- a/test/compliance/cases/stdlib/sort_enum_cases.phpt
+++ b/test/compliance/cases/stdlib/sort_enum_cases.phpt
@@ -1,9 +1,11 @@
 --TEST--
-stdlib sort() on enum case arrays preserves objects (#5546, ext/standard/array.c)
+stdlib sort() on enum case arrays preserves objects (#5546, #5691, ext/standard/array.c)
 --FILE--
 <?php
 enum EInt: int { case A = 1; case B = 2; case C = 3; }
 enum EUnit { case A; case B; }
+enum EStr: string { case A = 'b'; case B = 'a'; }
+enum EOrder: int { case C = 3; case A = 1; case B = 2; }
 
 $a = [EInt::C, EInt::A, EInt::B];
 sort($a);
@@ -16,9 +18,26 @@ sort($b);
 foreach ($b as $v) {
     echo $v->name, ($v instanceof EUnit ? '' : '!'), "\n";
 }
+
+$c = [EStr::B, EStr::A];
+sort($c);
+foreach ($c as $v) {
+    echo $v->name, ($v instanceof EStr ? '' : '!'), "\n";
+}
+
+$d = [EOrder::B, EOrder::C, EOrder::A];
+sort($d);
+foreach ($d as $v) {
+    echo $v->name, ($v instanceof EOrder ? '' : '!'), "\n";
+}
 --EXPECT--
 A
 B
 C
 A
 B
+A
+B
+A
+B
+C
diff --git a/test/unit/SortEnumCasesBuiltinTest.php b/test/unit/SortEnumCasesBuiltinTest.php
index 0df046d0a7e..6bd144db144 100644
--- a/test/unit/SortEnumCasesBuiltinTest.php
+++ b/test/unit/SortEnumCasesBuiltinTest.php
@@ -79,4 +79,38 @@ enum EInt: int { case A = 1; case B = 2; }
 
         $this->assertSame('B,A', $output);
     }
+
+    /** @covers issue #5691 */
+    public function testStringBackedEnumSortUsesObjectHandleOrder(): void
+    {
+        ob_start();
+        $runtime = new Runtime();
+        $runtime->run($runtime->parseAndCompile(<<<'PHP'
+<?php
+enum EStr: string { case A = 'b'; case B = 'a'; }
+$a = [EStr::B, EStr::A];
+sort($a);
+echo $a[0]->name, ',', $a[1]->name;
+PHP, 'sort_string_backed_enum.php'));
+        $output = ob_get_clean();
+
+        $this->assertSame('A,B', $output);
+    }
+
+    /** @covers issue #5691 */
+    public function testIntBackedEnumSortUsesDeclarationHandleNotBackingValue(): void
+    {
+        ob_start();
+        $runtime = new Runtime();
+        $runtime->run($runtime->parseAndCompile(<<<'PHP'
+<?php
+enum EOrder: int { case C = 3; case A = 1; case B = 2; }
+$a = [EOrder::B, EOrder::C, EOrder::A];
+sort($a);
+echo implode(',', array_map(fn($v) => $v->name, $a));
+PHP, 'sort_enum_declaration_order.php'));
+        $output = ob_get_clean();
+
+        $this->assertSame('C,A,B', $output);
+    }
 }