Index: wp-content/themes/twentyfifteen/inc/customizer.php
===================================================================
--- wp-content/themes/twentyfifteen/inc/customizer.php	(revision 30363)
+++ wp-content/themes/twentyfifteen/inc/customizer.php	(working copy)
@@ -18,7 +18,6 @@
 	$color_scheme = twentyfifteen_get_color_scheme();
 
 	$wp_customize->get_setting( 'blogname' )->transport        = 'postMessage';
-	$wp_customize->get_setting( 'blogdescription' )->transport = 'postMessage';
 
 	// Add color scheme setting and control.
 	$wp_customize->add_setting( 'color_scheme', array(
Index: wp-content/themes/twentyfifteen/js/customize-preview.js
===================================================================
--- wp-content/themes/twentyfifteen/js/customize-preview.js	(revision 30363)
+++ wp-content/themes/twentyfifteen/js/customize-preview.js	(working copy)
@@ -1,5 +1,5 @@
 /**
- * Live-update changed settings in real time in the Customizer preview. 
+ * Live-update changed settings in real time in the Customizer preview.
  */
 
 ( function( $ ) {
@@ -17,13 +17,6 @@
 		} );
 	} );
 
-	// Site tagline.
-	wp.customize( 'blogdescription', function( value ) {
-		value.bind( function( to ) {
-			$( '.site-description' ).text( to );
-		} );
-	} );
-
 	// Color Scheme CSS.
 	wp.customize( 'color_scheme_css', function( value ) {
 		value.bind( function( to ) {