diff --git a/core/assets/scaffold/files/default.services.yml b/core/assets/scaffold/files/default.services.yml
index ff6797d9..780f8f6b 100644
--- a/core/assets/scaffold/files/default.services.yml
+++ b/core/assets/scaffold/files/default.services.yml
@@ -53,6 +53,8 @@ parameters:
     # \Drupal\Core\Session\SessionConfiguration::__construct()
     # @default 6
     sid_bits_per_character: 6
+    # When generating unique session cookie name, add this string.
+    session_suffix: ''
   twig.config:
     # Twig debugging:
     #
diff --git a/core/core.services.yml b/core/core.services.yml
index 07def88b..f8f9849e 100644
--- a/core/core.services.yml
+++ b/core/core.services.yml
@@ -11,6 +11,7 @@ parameters:
     cookie_lifetime: 2000000
     sid_length: 48
     sid_bits_per_character: 6
+    session_suffix: ''
   twig.config:
     debug: false
     auto_reload: null
diff --git a/core/lib/Drupal/Core/Session/SessionConfiguration.php b/core/lib/Drupal/Core/Session/SessionConfiguration.php
index cecc0a35..d86aa142 100644
--- a/core/lib/Drupal/Core/Session/SessionConfiguration.php
+++ b/core/lib/Drupal/Core/Session/SessionConfiguration.php
@@ -27,7 +27,11 @@ class SessionConfiguration implements SessionConfigurationInterface {
   public function __construct($options = []) {
     // Provide sensible defaults for sid_length and sid_bits_per_character.
     // See core/assets/scaffold/files/default.services.yml for more information.
-    $this->options = $options + ['sid_length' => 48, 'sid_bits_per_character' => 6];
+    $this->options = $options + [
+        'sid_length' => 48,
+        'sid_bits_per_character' => 6,
+        'session_suffix' => '',
+      ];
   }
 
   /**
@@ -96,7 +100,7 @@ protected function getUnprefixedName(Request $request) {
     else {
       // Otherwise use $base_url as session name, without the protocol
       // to use the same session identifiers across HTTP and HTTPS.
-      $session_name = $request->getHost() . $request->getBasePath();
+      $session_name = $request->getHost() . $request->getBasePath() . $this->options['session_suffix'];
       // Replace "core" out of session_name so core scripts redirect properly,
       // specifically install.php.
       $session_name = preg_replace('#/core$#', '', $session_name);
diff --git a/core/tests/Drupal/Tests/Core/Session/SessionConfigurationTest.php b/core/tests/Drupal/Tests/Core/Session/SessionConfigurationTest.php
index ac6b0a76..e683b0b5 100644
--- a/core/tests/Drupal/Tests/Core/Session/SessionConfigurationTest.php
+++ b/core/tests/Drupal/Tests/Core/Session/SessionConfigurationTest.php
@@ -253,11 +253,13 @@ public function providerTestEnforcedSessionName() {
    *
    * @dataProvider providerTestConstructorDefaultSettings
    */
-  public function testConstructorDefaultSettings(array $options, int $expected_sid_length, int $expected_sid_bits_per_character) {
+  public function testConstructorDefaultSettings(array $options, int $expected_sid_length, int $expected_sid_bits_per_character, string $expected_session_suffix) {
+//    TODO
     $config = $this->createSessionConfiguration($options);
     $options = $config->getOptions(Request::createFromGlobals());
     $this->assertSame($expected_sid_length, $options['sid_length']);
     $this->assertSame($expected_sid_bits_per_character, $options['sid_bits_per_character']);
+    $this->assertSame($expected_session_suffix, $options['session_suffix']);
   }
 
   /**
@@ -268,10 +270,11 @@ public function testConstructorDefaultSettings(array $options, int $expected_sid
    */
   public function providerTestConstructorDefaultSettings() {
     return [
-      [[], 48, 6],
-      [['sid_length' => 100], 100, 6],
-      [['sid_bits_per_character' => 5], 48, 5],
-      [['sid_length' => 100, 'sid_bits_per_character' => 5], 100, 5],
+      [[], 48, 6, ''],
+      [['sid_length' => 100], 100, 6, ''],
+      [['sid_bits_per_character' => 5], 48, 5, ''],
+      [['session_suffix' => 'some-suffix'], 48, 6, 'some-suffix'],
+      [['sid_length' => 100, 'sid_bits_per_character' => 5, 'session_suffix' => 'some-suffix'], 100, 5, 'some-suffix'],
     ];
   }
 
diff --git a/sites/default/default.services.yml b/sites/default/default.services.yml
index ff6797d9..780f8f6b 100644
--- a/sites/default/default.services.yml
+++ b/sites/default/default.services.yml
@@ -53,6 +53,8 @@ parameters:
     # \Drupal\Core\Session\SessionConfiguration::__construct()
     # @default 6
     sid_bits_per_character: 6
+    # When generating unique session cookie name, add this string.
+    session_suffix: ''
   twig.config:
     # Twig debugging:
     #