A script that uses iio-sensor-proxy (the monitor-sensor command) to detect screen orientation changes and rotate the screen and any pointers (touchpad, touchscreen, pen) accordingly.
Put the script somewhere, make it executable, and start it when your desktop and/or window manager starts. For example, you could put this in your ~/.config/i3/config:
exec --no-startup-id /path/to/autorotate
NOTE: if you are not using an HP Spectre 13-ap0059dx like me, you will probably need to edit the script and change the device names. Run xinput list to see the names of your devices.