Use viminfo file relative to current working directory.
With Vim-plug (or your prefered way) :
call plug#begin()
Plug 'maxboisvert/vim-local-history'
call plug#end()
This plugin is useful with this mapping :
nnoremap <Leader>p :e **/*
After opening a file with this command, you can do :e <Up><Up>
to access the current project's history. This is like a MRU.
GPL3