Epic Games has begun published Vulkan support for using this next-gen, high-performance graphics API with Unreal Engine 4 for supported operating systems. The Vulkan code for UE4 is currently living here on GitHub. Note that to see it you must have access to the UE4 Git repository via your Epic Games' account. Of course, this addition isn't a big surprise given that Epic Games has been showing off UE4 Vulkan demos for a number of weeks already and they signaled their Vulkan interest and support intentions back on Vulkan's launch day.
Hopefully the UE4 Linux demos (that are benchmark friendly) will finally get rebuilt soon against the latest version of the Unreal Engine code-base.