Libreoffice 5.0 was just released.
tried
sudo add-apt-repository ppa:libreoffice/libreoffice-5.0
But
cannot add PPA: 'ppa:~libreoffice/ubuntu/libreoffice-5-0'.
The team named '~libreoffice' has no PPA named 'ubuntu/libreoffice-5-0'
Edit: You can add Libreofiice 5.0 using
sudo add-apt-repository -y ppa:libreoffice/ppa