How to flip a U-tile on the horizontal axis?

The mesh I playing around with in Unreal Engine has an image texture, but the mesh itself is symetrical which means to avoid having a double file size for the image texture, I can just apply the same texture through a U-tile. Problem is that I do not know how to flip one of the tiles on the horizontal axis. Any help?

Original texture in top left:

Probably easier to edit the texture…