Can you fill in a slope upwards with commands in Minecraft?

I want to fill in a slope upwards in Minecraft, I can't use the fill command because it only fills out cuboid areas.

An example: × This should represent a block.

X

. X

. X

The perspective is from above, and I want to fill this out 50 blocks up, so nothing should be changed. Do I have to use fill for every single block or is there a command with which you can do all of this at the same time?

Forget the example, doesn't work.

It works. It only took a long time to edit.