Index: src/wp-admin/includes/upgrade.php
===================================================================
--- src/wp-admin/includes/upgrade.php	(revision 35029)
+++ src/wp-admin/includes/upgrade.php	(working copy)
@@ -34,9 +34,10 @@
  * @param string $deprecated    Optional. Not used.
  * @param string $user_password Optional. User's chosen password. Default empty (random password).
  * @param string $language      Optional. Language chosen. Default empty.
+ * @param string $blog_tagline  Blog tagline.
  * @return array Array keys 'url', 'user_id', 'password', and 'password_message'.
  */
-function wp_install( $blog_title, $user_name, $user_email, $public, $deprecated = '', $user_password = '', $language = '' ) {
+function wp_install( $blog_title, $user_name, $user_email, $public, $deprecated = '', $user_password = '', $language = '', $blog_tagline = '' ) {
 	if ( !empty( $deprecated ) )
 		_deprecated_argument( __FUNCTION__, '2.6' );
 
@@ -54,6 +55,10 @@
 		update_option( 'WPLANG', $language );
 	}
 
+	if ( $blog_tagline ) {
+		update_option( 'blogdescription', $blog_tagline );
+	}
+
 	$guessurl = wp_guess_url();
 
 	update_option('siteurl', $guessurl);
Index: src/wp-admin/install.php
===================================================================
--- src/wp-admin/install.php	(revision 35029)
+++ src/wp-admin/install.php	(working copy)
@@ -101,6 +101,7 @@
 	}
 
 	$weblog_title = isset( $_POST['weblog_title'] ) ? trim( wp_unslash( $_POST['weblog_title'] ) ) : '';
+	$weblog_tagline = isset( $_POST['weblog_tagline'] ) ? trim( wp_unslash( $_POST['weblog_tagline'] ) ) : ''; 
 	$user_name = isset($_POST['user_name']) ? trim( wp_unslash( $_POST['user_name'] ) ) : '';
 	$admin_email  = isset( $_POST['admin_email']  ) ? trim( wp_unslash( $_POST['admin_email'] ) ) : '';
 
@@ -115,6 +116,10 @@
 			<td><input name="weblog_title" type="text" id="weblog_title" size="25" value="<?php echo esc_attr( $weblog_title ); ?>" /></td>
 		</tr>
 		<tr>
+			<th scope="row"><label for="weblog_tagline"><?php _e( 'Site Tagline' ); ?></label></th>
+			<td><input name="weblog_tagline" type="text" id="weblog_tagline" size="25" value="<?php echo esc_attr( $weblog_tagline ); ?>" /></td>
+		</tr>
+		<tr>
 			<th scope="row"><label for="user_login"><?php _e('Username'); ?></label></th>
 			<td>
 			<?php
@@ -306,6 +311,7 @@
 		display_header();
 		// Fill in the data we gathered
 		$weblog_title = isset( $_POST['weblog_title'] ) ? trim( wp_unslash( $_POST['weblog_title'] ) ) : '';
+		$weblog_tagline = isset( $_POST['weblog_tagline'] ) ? trim( wp_unslash( $_POST['weblog_tagline'] ) ) : ''; 
 		$user_name = isset($_POST['user_name']) ? trim( wp_unslash( $_POST['user_name'] ) ) : '';
 		$admin_password = isset($_POST['admin_password']) ? wp_unslash( $_POST['admin_password'] ) : '';
 		$admin_password_check = isset($_POST['admin_password2']) ? wp_unslash( $_POST['admin_password2'] ) : '';
@@ -337,7 +343,7 @@
 
 		if ( $error === false ) {
 			$wpdb->show_errors();
-			$result = wp_install( $weblog_title, $user_name, $admin_email, $public, '', wp_slash( $admin_password ), $loaded_language );
+			$result = wp_install( $weblog_title, $user_name, $admin_email, $public, '', wp_slash( $admin_password ), $loaded_language, $weblog_tagline );
 ?>
 
 <h1><?php _e( 'Success!' ); ?></h1>