Tyler Furby writes:

In an effort to bring industry standard tools to the free and open-source 3D computer graphics software Blender, a new add-on, Barnold, is currently in development which aims at bringing Solid Angle's unbiased, physically based, ray tracing 3D rendering application Arnold Render to Blender's tool-set.

Barnold aims at becoming a production ready add-on, allowing all features of Arnold to be used right within Blender's interface. The developer of this add-on, Tyler Furby, extends Ildar Nikolaev's work on the Barnold plugin from several years ago and is committed to ensuring this add-on supports all future versions of both Blender and Arnold in the years to come.

Barnold is currently in early beta and development is actively being worked on, if you would like to try it out yourself, you can download Barnold (beta) from GitHub.