Saving project with data source path as relative in QGIS?

Goto:

1. Settings
2. Project Properties..
3. Now check the general tab

you should see save paths and besides relativ ( I believe its even standard since vers. 1.73, before 1.73 the default was absolut)

Kurt

ps. just take at look at the screenshot made by manning above ;-)

pps: your screenshot is from settings --> options , thats the wrong way

Yes. In the Settings > Project Properties > General tab, there is an option to use Absolute or Relative path.

In version 2.18, the relative path was an option but didn't actually work.
Project ➜ Project Properties ➜ General ➜ General settings ➜ Save paths.

However, it does work in 3.2:
Project ➜ Properties ➜ General ➜ General settings ➜ Save paths.