2 files changed, 19 insertions, 1 deletions
diff --git a/actionpack/lib/action_dispatch/routing/redirection.rb b/actionpack/lib/action_dispatch/routing/redirection.rb
index 68094f129f..3e54c7e71c 100644
--- a/actionpack/lib/action_dispatch/routing/redirection.rb
+++ b/actionpack/lib/action_dispatch/routing/redirection.rb
@@ -30,6 +30,10 @@ module ActionDispatch
         uri.host   ||= req.host
         uri.port   ||= req.port unless req.standard_port?
 
+        if relative_path?(uri.path)
+          uri.path = "#{req.script_name}/#{uri.path}"
+        end
+
         body = %(<html><body>You are being <a href="#{ERB::Util.h(uri.to_s)}">redirected</a>.</body></html>)
 
         headers = {
@@ -48,6 +52,11 @@ module ActionDispatch
       def inspect
         "redirect(#{status})"
       end
+
+      private
+        def relative_path?(path)
+          path && !path.empty? && path[0] != '/'
+        end
     end
 
     class PathRedirect < Redirect
@@ -81,6 +90,11 @@ module ActionDispatch
           url_options[:path] = (url_options[:path] % escape_path(params))
         end
 
+        if relative_path?(url_options[:path])
+          url_options[:path] = "/#{url_options[:path]}"
+          url_options[:script_name] = request.script_name
+        end
+
         ActionDispatch::Http::URL.url_for url_options
       end
 
@@ -104,6 +118,10 @@ module ActionDispatch
       #
       #   get 'docs/:article', to: redirect('/wiki/%{article}')
       #
+      # Note that if you return a path without a leading slash then the url is prefixed with the
+      # current SCRIPT_NAME environment variable. This is typically '/' but may be different in
+      # a mounted engine or where the application is deployed to a subdirectory of a website.
+      #
       # Alternatively you can use one of the other syntaxes:
       #
       # The block version of redirect allows for the easy encapsulation of any logic associated with
diff --git a/actionpack/lib/action_dispatch/routing/url_for.rb b/actionpack/lib/action_dispatch/routing/url_for.rb
index 8e19025722..bcebe532bf 100644
--- a/actionpack/lib/action_dispatch/routing/url_for.rb
+++ b/actionpack/lib/action_dispatch/routing/url_for.rb
@@ -20,7 +20,7 @@ module ActionDispatch
     #
     #   <%= link_to('Click here', controller: 'users',
     #           action: 'new', message: 'Welcome!') %>
-    #   # => "/users/new?message=Welcome%21"
+    #   # => <a href="/users/new?message=Welcome%21">Click here</a>
     #
     # link_to, and all other functions that require URL generation functionality,
     # actually use ActionController::UrlFor under the hood. And in particular,