Index: src/wp-admin/includes/class-wp-site-icon.php
===================================================================
--- src/wp-admin/includes/class-wp-site-icon.php	(revision 33173)
+++ src/wp-admin/includes/class-wp-site-icon.php	(working copy)
@@ -266,7 +266,7 @@
 			<div class="site-icon-crop-shell">
 				<form action="options-general.php" method="post" enctype="multipart/form-data">
 					<p class="hide-if-no-js description"><?php _e('Choose the part of the image you want to use as your site icon.'); ?></p>
-					<p class="hide-if-js description"><strong><?php _e( 'You need Javascript to choose a part of the image.'); ?></strong></p>
+					<p class="hide-if-js description"><strong><?php _e( 'You need JavaScript to choose a part of the image.'); ?></strong></p>
 
 					<div class="site-icon-crop-wrapper">
 						<img src="<?php echo esc_url( $url ); ?>" id="crop-image" class="site-icon-crop-image" width="512" height="" alt="<?php esc_attr_e( 'Image to be cropped' ); ?>"/>
@@ -273,13 +273,13 @@
 					</div>
 
 					<div class="site-icon-crop-preview-shell hide-if-no-js">
-						<h3><?php _e( 'Preview' ); ?></h3>
+						<h2><?php _e( 'Preview' ); ?></h2>
 						<strong><?php _e( 'As a browser icon' ); ?></strong>
 						<div class="site-icon-crop-favicon-preview-shell">
-							<img src="images/browser.png" class="site-icon-browser-preview" width="182" height="" alt="<?php esc_attr_e( 'Browser Chrome' ); ?>"/>
+							<img src="images/browser.png" class="site-icon-browser-preview" width="182" height="" alt=""/>
 
 							<div class="site-icon-crop-preview-favicon">
-								<img src="<?php echo esc_url( $url ); ?>" id="preview-favicon" alt="<?php esc_attr_e( 'Preview Favicon' ); ?>"/>
+								<img src="<?php echo esc_url( $url ); ?>" id="preview-favicon" alt="<?php esc_attr_e( 'Preview as a browser icon' ); ?>"/>
 							</div>
 							<span class="site-icon-browser-title"><?php bloginfo( 'name' ); ?></span>
 						</div>
@@ -286,7 +286,7 @@
 
 						<strong><?php _e( 'As an app icon' ); ?></strong>
 						<div class="site-icon-crop-preview-homeicon">
-							<img src="<?php echo esc_url( $url ); ?>" id="preview-homeicon" alt="<?php esc_attr_e( 'Preview Home Icon' ); ?>"/>
+							<img src="<?php echo esc_url( $url ); ?>" id="preview-homeicon" alt="<?php esc_attr_e( 'Preview as an app icon' ); ?>"/>
 						</div>
 					</div>
 
Index: src/wp-admin/options-general.php
===================================================================
--- src/wp-admin/options-general.php	(revision 33173)
+++ src/wp-admin/options-general.php	(working copy)
@@ -125,7 +125,7 @@
 <p class="description" id="tagline-description"><?php _e( 'In a few words, explain what this site is about.' ) ?></p></td>
 </tr>
 <tr>
-<th scope="row"><label for="site_icon"><?php _e( 'Site Icon' ); ?></label></th>
+<th scope="row"><?php _e( 'Site Icon' ); ?></th>
 <td>
 	<?php
 	$upload_url = admin_url( 'options-general.php?page=site-icon' );
@@ -143,9 +143,8 @@
 		), wp_nonce_url( admin_url( 'options-general.php' ), 'remove-site-icon' ) );
 	?>
 
-	<img class="avatar avatar-150" src="<?php site_icon_url( null, 150 ); ?>" height="150" width="150" />
+	<img class="avatar avatar-150" src="<?php site_icon_url( null, 150 ); ?>" height="150" width="150" alt="" />
 	<p class="hide-if-no-js">
-		<label class="screen-reader-text" for="choose-from-library-link"><?php _e( 'Choose an image from your media library:' ); ?></label>
 		<button type="button" id="choose-from-library-link" class="button" data-size="<?php echo absint( $GLOBALS['wp_site_icon']->min_size ); ?>" data-update-link="<?php echo esc_attr( $update_url ); ?>" data-choose="<?php esc_attr_e( 'Choose a Site Icon' ); ?>" data-update="<?php esc_attr_e( 'Set as Site Icon' ); ?>"><?php _e( 'Update Site Icon' ); ?></button>
 		<a href="<?php echo esc_url( $remove_url ); ?>"><?php _e( 'Remove Site Icon' ); ?></a>
 	</p>
@@ -157,13 +156,12 @@
 	<?php else : ?>
 
 	<p class="hide-if-no-js">
-		<label class="screen-reader-text" for="choose-from-library-link"><?php _e( 'Choose an image from your media library:' ); ?></label>
-		<button type="button" id="choose-from-library-link" class="button" data-size="<?php echo absint( $GLOBALS['wp_site_icon']->min_size ); ?>" data-update-link="<?php echo esc_attr( $update_url ); ?>" data-choose="<?php esc_attr_e( 'Choose a Site Icon' ); ?>" data-update="<?php esc_attr_e( 'Set as Site Icon' ); ?>"><?php _e( 'Choose Image' ); ?></button>
+		<button type="button" id="choose-from-library-link" class="button" data-size="<?php echo absint( $GLOBALS['wp_site_icon']->min_size ); ?>" data-update-link="<?php echo esc_attr( $update_url ); ?>" data-choose="<?php esc_attr_e( 'Choose a Site Icon' ); ?>" data-update="<?php esc_attr_e( 'Set as Site Icon' ); ?>" aria-label="<?php esc_attr_e( 'Choose an image from your media library' ); ?>" aria-describedby="site-icon-desc"><?php _e( 'Choose Image' ); ?></button>
 	</p>
 	<a class="button hide-if-js" href="<?php echo esc_url( $upload_url ); ?>"><?php _e( 'Add a Site Icon' ); ?></a>
 
 	<?php endif; ?>
-	<p class="description"><?php _e( 'The Site Icon is used as a browser and app icon for your site.' ); ?></p>
+	<p class="description" id="site-icon-desc"><?php _e( 'The Site Icon is used as a browser and app icon for your site.' ); ?></p>
 </td>
 </tr>
 <?php if ( !is_multisite() ) { ?>