diff --git a/src/Symfony/Bridge/Twig/Resources/views/Form/bootstrap_4_layout.html.twig b/src/Symfony/Bridge/Twig/Resources/views/Form/bootstrap_4_layout.html.twig
index 03109bdf6cac2..1848d0dc9838c 100644
--- a/src/Symfony/Bridge/Twig/Resources/views/Form/bootstrap_4_layout.html.twig
+++ b/src/Symfony/Bridge/Twig/Resources/views/Form/bootstrap_4_layout.html.twig
@@ -122,7 +122,8 @@
     <{{ element|default('div') }} class="custom-file">
         {%- set type = type|default('file') -%}
         {{- block('form_widget_simple') -}}
-        <label for="{{ form.vars.id }}" class="custom-file-label">
+        {%- set label_attr = label_attr|merge({ class: (label_attr.class|default('') ~ ' custom-file-label')|trim }) -%}
+        <label for="{{ form.vars.id }}" {% with { attr: label_attr } %}{{ block('attributes') }}{% endwith %}>
             {%- if attr.placeholder is defined -%}
                 {{- translation_domain is same as(false) ? attr.placeholder : attr.placeholder|trans({}, translation_domain) -}}
             {%- endif -%}