Index: wp-admin/css/customize-controls.css
===================================================================
--- wp-admin/css/customize-controls.css	(revision 29831)
+++ wp-admin/css/customize-controls.css	(working copy)
@@ -268,6 +268,29 @@
 	height: 22px;
 }
 
+.control-section .accordion-section-title {
+	padding-left: 45px;
+}
+
+.in-sub-panel .control-section .accordion-section-title {
+	padding-left: 14px;
+}
+
+.in-sub-panel .control-section .accordion-section-title:before {
+	display: none;
+}
+
+.control-section .accordion-section-title:before {
+	font: normal 20px/1 dashicons;
+	position: absolute;
+	top: 11px;
+	left: 14px;
+	-webkit-font-smoothing: antialiased;
+	-moz-osx-font-smoothing: grayscale;
+}
+
+/* Don't override custom icons, which get an additional class. */
+.control-panel > [class="accordion-section-title "]:before,
+.control-section > [class="accordion-section-title "]:before {
+	content: "\f111";
+}
+
 .wp-full-overlay-sidebar .wp-full-overlay-header {
 	-webkit-transition: padding ease-in-out .18s;
 	transition: padding ease-in-out .18s;
Index: wp-content/themes/twentyeleven/inc/theme-options.php
===================================================================
--- wp-content/themes/twentyeleven/inc/theme-options.php	(revision 29831)
+++ wp-content/themes/twentyeleven/inc/theme-options.php	(working copy)
@@ -550,6 +550,7 @@
 	// Default Layout
 	$wp_customize->add_section( 'twentyeleven_layout', array(
 		'title'    => __( 'Layout', 'twentyeleven' ),
+		'icon'     => 'dashicons-align-right',
 		'priority' => 50,
 	) );
 
Index: wp-content/themes/twentyfourteen/inc/customizer.php
===================================================================
--- wp-content/themes/twentyfourteen/inc/customizer.php	(revision 29831)
+++ wp-content/themes/twentyfourteen/inc/customizer.php	(working copy)
@@ -38,6 +38,7 @@
 	// Add the featured content section in case it's not already there.
 	$wp_customize->add_section( 'featured_content', array(
 		'title'       => __( 'Featured Content', 'twentyfourteen' ),
+		'icon'        => 'dashicons-star-filled',
 		'description' => sprintf( __( 'Use a <a href="%1$s">tag</a> to feature your posts. If no posts match the tag, <a href="%2$s">sticky posts</a> will be displayed instead.', 'twentyfourteen' ),
 			esc_url( add_query_arg( 'tag', _x( 'featured', 'featured content default tag slug', 'twentyfourteen' ), admin_url( 'edit.php' ) ) ),
 			admin_url( 'edit.php?show_sticky=1' )
Index: src/wp-includes/class-wp-customize-manager.php
===================================================================
--- wp-includes/class-wp-customize-manager.php	(revision 29831)
+++ wp-includes/class-wp-customize-manager.php	(working copy)
@@ -931,6 +931,7 @@
 
 		$this->add_section( 'title_tagline', array(
 			'title'    => __( 'Site Title & Tagline' ),
+			'icon'     => 'dashicons-feedback',
 			'priority' => 20,
 		) );
 
@@ -960,6 +961,7 @@
 
 		$this->add_section( 'colors', array(
 			'title'          => __( 'Colors' ),
+			'icon'           => 'dashicons-art',
 			'priority'       => 40,
 		) );
 
@@ -1005,6 +1007,7 @@
 
 		$this->add_section( 'header_image', array(
 			'title'          => __( 'Header Image' ),
+			'icon'           => 'dashicons-camera',
 			'theme_supports' => 'custom-header',
 			'priority'       => 60,
 		) );
@@ -1025,6 +1028,7 @@
 
 		$this->add_section( 'background_image', array(
 			'title'          => __( 'Background Image' ),
+			'icon'           => 'dashicons-format-image',
 			'theme_supports' => 'custom-background',
 			'priority'       => 80,
 		) );
@@ -1104,6 +1108,7 @@
 
 		$this->add_section( 'nav', array(
 			'title'          => __( 'Navigation' ),
+			'icon'           => 'dashicons-menu',
 			'theme_supports' => 'menus',
 			'priority'       => 100,
 			'description'    => sprintf( _n('Your theme supports %s menu. Select which menu you would like to use.', 'Your theme supports %s menus. Select which menu appears in each location.', $num_locations ), number_format_i18n( $num_locations ) ) . "\n\n" . __('You can edit your menu content on the Menus screen in the Appearance section.'),
@@ -1137,6 +1142,7 @@
 
 		$this->add_section( 'static_front_page', array(
 			'title'          => __( 'Static Front Page' ),
+			'icon'           => 'dashicons-admin-post',
 		//	'theme_supports' => 'static-front-page',
 			'priority'       => 120,
 			'description'    => __( 'Your theme supports a static front page.' ),
Index: wp-includes/class-wp-customize-panel.php
===================================================================
--- wp-includes/class-wp-customize-panel.php	(revision 29831)
+++ wp-includes/class-wp-customize-panel.php	(working copy)
@@ -74,6 +74,15 @@
 	public $description = '';
 
 	/**
+	 * Dasicon for this panel.
+	 *
+	 * @since 4.1.0
+	 * @access public
+	 * @var string
+	 */
+	public $icon = '';
+
+	/**
 	 * Customizer sections for this panel.
 	 *
 	 * @since 4.0.0
@@ -170,7 +179,7 @@
 	protected function render() {
 		?>
 		<li id="accordion-panel-<?php echo esc_attr( $this->id ); ?>" class="control-section control-panel accordion-section">
-			<h3 class="accordion-section-title" tabindex="0">
+			<h3 class="accordion-section-title <?php echo $this->icon; ?>" tabindex="0">
 				<?php echo esc_html( $this->title ); ?>
 				<span class="screen-reader-text"><?php _e( 'Press return or enter to open this panel' ); ?></span>
 			</h3>
Index: wp-includes/class-wp-customize-section.php
===================================================================
--- wp-includes/class-wp-customize-section.php	(revision 29831)
+++ wp-includes/class-wp-customize-section.php	(working copy)
@@ -83,6 +83,15 @@
 	public $description = '';
 
 	/**
+	 * Dasicon for the section.
+	 *
+	 * @since 4.1.0
+	 * @access public
+	 * @var string
+	 */
+	public $icon = '';
+
+	/**
 	 * Customizer controls for this section.
 	 *
 	 * @since 3.4.0
@@ -177,7 +186,7 @@
 		}
 		?>
 		<li id="accordion-section-<?php echo esc_attr( $this->id ); ?>" class="<?php echo esc_attr( $classes ); ?>">
-			<h3 class="accordion-section-title" tabindex="0">
+			<h3 class="accordion-section-title <?php echo $this->icon; ?>" tabindex="0">
 				<?php echo esc_html( $this->title ); ?>
 				<span class="screen-reader-text"><?php _e( 'Press return or enter to expand' ); ?></span>
 			</h3>
Index: wp-includes/class-wp-customize-widgets.php
===================================================================
--- wp-includes/class-wp-customize-widgets.php	(revision 29831)
+++ wp-includes/class-wp-customize-widgets.php	(working copy)
@@ -435,6 +435,7 @@
 
 		$this->manager->add_panel( 'widgets', array(
 			'title'       => __( 'Widgets' ),
+			'icon'        => 'dashicons-welcome-widgets-menus',
 			'description' => __( 'Widgets are independent sections of content that can be placed into widgetized areas provided by your theme (commonly called sidebars).' ),
 			'priority'    => 110,
 		) );