Depends on the failure mode.
There is an epoxy putty that I used for a small, (1/2" long), split in a copper pipe.

Drain the water, dry and clean the pipe.
Knead the yellow and blue putty until it turns uniformly green.

(Hmmm, the stuff on amazon isn't yellow and blue, that was a nice feature.
Anyroad, the local H.D. or Lowes should have it.)

Then pack it tightly around the pipe and wrap very tightly with strips of cotton cloth.
Let it set for the recommended time.
Then, let it set for a bit more.

When you turn the water back on, do it very slowly with a downstream tap open.
Then, turn that tap off, slowly, and check for leaks as the pressure rises.
Mine lasted 15 years that I know of.
Was still holding when I sold the house.

"We don't need no steenking plumbers!"

Aloha,
Weeze