diff --git a/libs/ardour/ardour/route.h b/libs/ardour/ardour/route.h
index edad4fd266..44069462d1 100644
--- a/libs/ardour/ardour/route.h
+++ b/libs/ardour/ardour/route.h
@@ -567,6 +567,14 @@ class LIBARDOUR_API Route : public SessionObject, public Automatable, public Rou
          */
         std::string send_name (uint32_t n) const;
 
+        /* well known control that enables/disables sending to the master bus.
+         *
+         * In Ardour, this returns null.
+         * In Mixbus, it will return a suitable control, or null depending on
+         * the route.
+         */
+        boost::shared_ptr<AutomationControl> master_send_enable_controllable () const;
+
         void protect_automation ();
 
 	enum {
diff --git a/libs/ardour/route.cc b/libs/ardour/route.cc
index 6effb27fc4..fb417305d7 100644
--- a/libs/ardour/route.cc
+++ b/libs/ardour/route.cc
@@ -5571,3 +5571,15 @@ Route::send_name (uint32_t n) const
 	}
 #endif
 }
+
+boost::shared_ptr<AutomationControl>
+Route::master_send_enable_controllable () const
+{
+#ifdef  MIXBUS
+	boost::shared_ptr<ARDOUR::PluginInsert> plug = ch_post();
+	assert (plug);
+	return boost::dynamic_pointer_cast<ARDOUR::AutomationControl> (plug->control (Evoral::Parameter (ARDOUR::PluginAutomation, 0, port_channel_post_mstr_assign)));
+#else
+	return boost::shared_ptr<AutomationControl>();
+#endif
+}