Index: src/wp-includes/formatting.php
===================================================================
--- src/wp-includes/formatting.php	(revision 35750)
+++ src/wp-includes/formatting.php	(working copy)
@@ -3706,7 +3706,6 @@
 			if ( is_wp_error( $value ) ) {
 				$error = $value->get_error_message();
 			} else {
-				$value = wp_kses_post( $value );
 				$value = esc_html( $value );
 			}
 			break;
Index: tests/phpunit/tests/formatting/BlogInfo.php
===================================================================
--- tests/phpunit/tests/formatting/BlogInfo.php	(revision 35750)
+++ tests/phpunit/tests/formatting/BlogInfo.php	(working copy)
@@ -31,4 +31,30 @@
 			array( 'pt_PT_ao1990', 'pt-PT-ao1990' ),
 		);
 	}
+
+	/**
+	 * @ticket 27942
+	 */
+	function test_bloginfo_blogname() {
+		$old_value = get_option( 'blogname' );
+
+		$options = array(
+			'foo' => 'foo',
+			'<em>foo</em>' => '&lt;em&gt;foo&lt;/em&gt;',
+			'<script>foo</script>' => '&lt;script&gt;foo&lt;/script&gt;',
+			'&lt;foo&gt;' => '&lt;foo&gt;',
+			'<foo' => '&lt;foo',
+		);
+
+		foreach ( $options as $value => $expected ) {
+			$sanitized_value = sanitize_option( 'blogname', $value );
+			update_option( 'blogname', $sanitized_value );
+
+			$this->assertEquals( $expected, $sanitized_value );
+			$this->assertEquals( $expected, get_bloginfo( 'blogname' ) );
+			$this->assertEquals( $expected, get_bloginfo( 'blogname', 'display' ) );
+		}
+
+		update_option( 'blogname', $old_value );
+	}
 }