Index: src/wp-admin/includes/upgrade.php
===================================================================
--- src/wp-admin/includes/upgrade.php	(revision 31057)
+++ src/wp-admin/includes/upgrade.php	(working copy)
@@ -75,30 +75,32 @@
 		update_user_option($user_id, 'default_password_nag', true, true);
 		$email_password = true;
 	} else if ( !$user_id ) {
 		// Password has been provided
 		$message = '<em>'.__('Your chosen password.').'</em>';
 		$user_id = wp_create_user($user_name, $user_password, $user_email);
 	} else {
 		$message = __('User already exists. Password inherited.');
 	}
 
 	$user = new WP_User($user_id);
 	$user->set_role('administrator');
 
 	wp_install_defaults($user_id);
 
+	wp_install_maybe_pretty_permalinks();
+
 	flush_rewrite_rules();
 
 	wp_new_blog_notification($blog_title, $guessurl, $user_id, ($email_password ? $user_password : __('The password you chose during the install.') ) );
 
 	wp_cache_flush();
 
 	/**
 	 * Fires after a site is fully installed.
 	 *
 	 * @since 3.9.0
 	 *
 	 * @param WP_User $user The site owner.
 	 */
 	do_action( 'wp_install', $user );
 
@@ -248,30 +250,104 @@
 
 		$user = new WP_User($user_id);
 		$wpdb->update( $wpdb->options, array('option_value' => $user->user_email), array('option_name' => 'admin_email') );
 
 		// Remove all perms except for the login user.
 		$wpdb->query( $wpdb->prepare("DELETE FROM $wpdb->usermeta WHERE user_id != %d AND meta_key = %s", $user_id, $table_prefix.'user_level') );
 		$wpdb->query( $wpdb->prepare("DELETE FROM $wpdb->usermeta WHERE user_id != %d AND meta_key = %s", $user_id, $table_prefix.'capabilities') );
 
 		// Delete any caps that snuck into the previously active blog. (Hardcoded to blog 1 for now.) TODO: Get previous_blog_id.
 		if ( !is_super_admin( $user_id ) && $user_id != 1 )
 			$wpdb->delete( $wpdb->usermeta, array( 'user_id' => $user_id , 'meta_key' => $wpdb->base_prefix.'1_capabilities' ) );
 	}
 }
 endif;
 
+if ( ! function_exists( 'wp_install_maybe_pretty_permalinks' ) ) :
+/**
+ * Enable pretty permalinks if available.
+ *
+ * This function will enable pretty permalinks if it can verify they work.
+ * If all pretty permalinks formats fail to work, WordPress will fall back
+ * to ugly permalinks by setting an empty permalink structure.
+ *
+ * @since 4.2.0
+ *
+ * @global WP_Rewrite $wp_rewrite WordPress rewrite component.
+ */
+function wp_install_maybe_pretty_permalinks() {
+	global $wp_rewrite;
+
+	/*
+	 * Bail if we alredy have permalinks enabled (Multisite)
+	 */
+	if ( get_option( 'permalink_structure' ) ) {
+		return;
+	}
+
+	/*
+	 * The Permalink structures which WordPress should attempt to use.
+	 * The first is designed for mod_rewrite or nginx rewriting.
+	 * The second is PATHINFO based permalinks offered under configurations without rewrites enabled.
+	 */
+	$permalink_structures = array(
+		'/%year%/%monthnum%/%day%/%postname%/',
+		'/index.php/%year%/%monthnum%/%day%/%postname%/'
+	);
+
+	foreach ( $permalink_structures as $permalink_structure ) {
+		/*
+		 * Set the desired Permalink structure to try
+		 */
+		$wp_rewrite->set_permalink_structure( $permalink_structure );
+
+		/*
+	 	 * Flush rules with the hard option to force refresh of the web-server's
+	 	 * rewrite config file (e.g. .htaccess or web.config).
+	 	 */
+		$wp_rewrite->flush_rules( true );
+
+		/*
+		 * Test against a real WordPress Post, or if none were created, a Page URI
+		 */
+		$test_url = get_permalink( 1 );
+		if ( ! $test_url ) {
+			$test_url = home_url( '/wordpress-check-for-rewrites/' );
+		}
+
+		/*
+	 	 * Send a HEAD request to a random page on the site, and check whether
+	 	 * the 'x-pingback' header is returned as expected.
+	 	 */
+		$response          = wp_remote_get( $test_url, array( 'timeout' => 5 ) );
+		$x_pingback_header = wp_remote_retrieve_header( $response, 'x-pingback' );
+		$pretty_permalinks = $x_pingback_header && $x_pingback_header === get_bloginfo( 'pingback_url' );
+
+		if ( $pretty_permalinks ) {
+			return true;
+		}
+	}
+
+	/*
+	 * If it makes it this far, Pretty Permalinks failed to activate.
+	 * Reset and allow the user to select it themselves.
+	 */
+	$wp_rewrite->set_permalink_structure( '' );
+	$wp_rewrite->flush_rules( true );
+}
+endif;
+
 if ( !function_exists('wp_new_blog_notification') ) :
 /**
  * {@internal Missing Short Description}}
  *
  * {@internal Missing Long Description}}
  *
  * @since 2.1.0
  *
  * @param string $blog_title Blog title.
  * @param string $blog_url Blog url.
  * @param int $user_id User ID.
  * @param string $password User's Password.
  */
 function wp_new_blog_notification($blog_title, $blog_url, $user_id, $password) {
 	$user = new WP_User( $user_id );