Vbulletin won't read PHP Maximum Upload Size correctly when using HHVM

[Karabaja]

My hosting suggested using hhvm as a better alternative to apache+php, or rather less prone to exploits and able to handle more load. Anyway atm we are using hhvm-fastcgi-nginx combination. Using VB 3.8.7. PHP: 5.6.99-hhvm

Even though upload_max_filesize in php.ini is set to 60M vbulletin seems to have uploads limited to 10MB.
In admin panel main page it reads:

PHP Max Post Size 	N/A
PHP Maximum Upload Size 	N/A

When I ran diagnostics and check file upload here is what it reads:

Pertinent PHP Settings
file_uploads: On
open_basedir: None
safe_mode: Off
upload_tmp_dir: /tmp
upload_max_filesize: 10.00 MB

I realize vbulletin has no support for HHVM but I was hoping someone at least has a clue as to where it picks up 10MB limit from and maybe I can change it somehow. I imagine if it can't read the value from php.ini it defaults to this value.