diff --git a/wp-includes/media.php b/wp-includes/media.php
index 04fb27608a..0da68e3d43 100644
--- a/wp-includes/media.php
+++ b/wp-includes/media.php
@@ -5643,6 +5643,11 @@ function wp_get_loading_optimization_attributes( $tag_name, $attr, $context ) {
 		return $postprocess( $loading_attrs, true );
 	}
 
+	// The custom header image is always expected to be in the header.
+	if ( 'get_header_image_tag' === $context ) {
+		return $postprocess( $loading_attrs, true );
+	}
+
 	// Special handling for programmatically created image tags.
 	if ( 'the_post_thumbnail' === $context || 'wp_get_attachment_image' === $context ) {
 		/*
diff --git a/wp-includes/theme.php b/wp-includes/theme.php
index 32fd55df5e..dfc0a4e063 100644
--- a/wp-includes/theme.php
+++ b/wp-includes/theme.php
@@ -1237,10 +1237,11 @@ function get_header_image_tag( $attr = array() ) {
 	$attr = wp_parse_args(
 		$attr,
 		array(
-			'src'    => $header->url,
-			'width'  => $width,
-			'height' => $height,
-			'alt'    => $alt,
+			'src'      => $header->url,
+			'width'    => $width,
+			'height'   => $height,
+			'alt'      => $alt,
+			'decoding' => 'async',
 		)
 	);
 
@@ -1265,6 +1266,29 @@ function get_header_image_tag( $attr = array() ) {
 		}
 	}
 
+	$attr = array_merge(
+		$attr,
+		wp_get_loading_optimization_attributes( 'img', $attr, 'get_header_image_tag' )
+	);
+
+	/*
+	 * If the default value of `lazy` for the `loading` attribute is overridden
+	 * to omit the attribute for this image, ensure it is not included.
+	 */
+	if ( isset( $attr['loading'] ) && ! $attr['loading'] ) {
+		unset( $attr['loading'] );
+	}
+
+	// If the `fetchpriority` attribute is overridden and set to false or an empty string.
+	if ( isset( $attr['fetchpriority'] ) && ! $attr['fetchpriority'] ) {
+		unset( $attr['fetchpriority'] );
+	}
+
+	// If the `decoding` attribute is overridden and set to false or an empty string.
+	if ( isset( $attr['decoding'] ) && ! $attr['decoding'] ) {
+		unset( $attr['decoding'] );
+	}
+
 	/**
 	 * Filters the list of header image attributes.
 	 *
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 2560c7180a..44d90d40dd 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.3-beta3-56141';
+$wp_version = '6.3-beta3-56142';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.