diff --git a/core/modules/system/src/Tests/Installer/InstallerSiteConfigDefaultTest.php b/core/modules/system/src/Tests/Installer/InstallerSiteConfigDefaultTest.php
new file mode 100644
index 0000000000..1117bea095
--- /dev/null
+++ b/core/modules/system/src/Tests/Installer/InstallerSiteConfigDefaultTest.php
@@ -0,0 +1,33 @@
+<?php
+
+namespace Drupal\system\Tests\Installer;
+
+use Drupal\simpletest\InstallerTestBase;
+
+/**
+ * Verifies that the installer defaults to using the system email address and
+ * timezone.
+ *
+ * @group Installer
+ */
+class InstallerSiteConfigDefaultTest extends InstallerTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUpSite() {
+    $this->assertFieldByName('site_mail', ini_get('sendmail_from'));
+    $this->assertFieldByName('date_default_timezone', @date_default_timezone_get());
+
+    return parent::setUpSite();
+  }
+
+  /**
+   * Verify the correct site config was set.
+   */
+  public function testInstaller() {
+    $this->assertEqual(\Drupal::config('system.site')->get('mail'), $this->parameters['forms']['install_configure_form']['site_mail']);
+    $this->assertEqual(\Drupal::config('system.date')->get('timezone.default'), @date_default_timezone_get());
+  }
+
+}
diff --git a/core/modules/system/src/Tests/Installer/InstallerSiteConfigProfileTest.php b/core/modules/system/src/Tests/Installer/InstallerSiteConfigProfileTest.php
new file mode 100644
index 0000000000..08ba200e38
--- /dev/null
+++ b/core/modules/system/src/Tests/Installer/InstallerSiteConfigProfileTest.php
@@ -0,0 +1,79 @@
+<?php
+
+namespace Drupal\system\Tests\Installer;
+
+use Drupal\simpletest\InstallerTestBase;
+
+/**
+ * Verifies that the installer defaults to the existing site email address and
+ * timezone, if they were provided by the install profile.
+ *
+ * @group Installer
+ */
+class InstallerSiteConfigProfileTest extends InstallerTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $profile = 'testing_site_config';
+
+  /**
+   * The site mail we expect to be set.
+   *
+   * @see testing_site_config_install()
+   */
+  const EXPECTED_SITE_MAIL = 'profile-testing-site-config@example.com';
+
+  /**
+   * The timezone we expect to be set. Determined dynamically in setUpSite().
+   *
+   * @see testing_site_config_install()
+   */
+  protected $expectedTimezone;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    // The install profile set the timezone to one of two possibilities, but
+    // never to the system timezone. (See testing_site_config.install.)
+    $this->expectedTimezone = 'America/Los_Angeles';
+    if ($this->expectedTimezone == @date_default_timezone_get()) {
+      $this->expectedTimezone = 'America/New_York';
+    }
+
+    return parent::setUp();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function installParameters() {
+    $parameters = parent::installParameters();
+
+    // Don't override the site email address, allowing it to default to the one
+    // from our install profile.
+    unset($parameters['forms']['install_configure_form']['site_mail']);
+
+    return $parameters;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUpSite() {
+    $this->assertFieldByName('site_mail', self::EXPECTED_SITE_MAIL);
+    $this->assertFieldByName('date_default_timezone', $this->expectedTimezone);
+
+    return parent::setUpSite();
+  }
+
+  /**
+   * Verify the correct site config was set.
+   */
+  public function testInstaller() {
+    $this->assertEqual(\Drupal::config('system.site')->get('mail'), self::EXPECTED_SITE_MAIL);
+    $this->assertEqual(\Drupal::config('system.date')->get('timezone.default'), $this->expectedTimezone);
+  }
+
+}
diff --git a/core/profiles/testing_site_config/testing_site_config.info.yml b/core/profiles/testing_site_config/testing_site_config.info.yml
new file mode 100644
index 0000000000..31a390557e
--- /dev/null
+++ b/core/profiles/testing_site_config/testing_site_config.info.yml
@@ -0,0 +1,6 @@
+name: Testing site config
+type: profile
+description: 'Minimal profile for testing with default site config.'
+version: VERSION
+core: 8.x
+hidden: true
diff --git a/core/profiles/testing_site_config/testing_site_config.install b/core/profiles/testing_site_config/testing_site_config.install
new file mode 100644
index 0000000000..954e4a0b66
--- /dev/null
+++ b/core/profiles/testing_site_config/testing_site_config.install
@@ -0,0 +1,20 @@
+<?php
+
+/**
+ * Implements hook_install().
+ */
+function testing_site_config_install() {
+  // Set the site email address to something that is not sendmail_from.
+  \Drupal::configFactory()->getEditable('system.site')
+    ->set('mail', 'profile-testing-site-config@example.com')
+    ->save(TRUE);
+
+  // Set the time zone to something that is not the system timezone.
+  $timezone = 'America/Los_Angeles';
+  if ($timezone == @date_default_timezone_get()) {
+    $timezone = 'America/New_York';
+  }
+  \Drupal::configFactory()->getEditable('system.date')
+    ->set('timezone.default', $timezone)
+    ->save(TRUE);
+}