[sigmoid10]

Probably because the upgrades to the collider are so significant that it will be called the HL-LHC afterwards.

[jdironman]

Hella Large - Large Hadron Collider?

[someonebaggy]

I think it stands for Huge Large Large Huge Colossal, in reference to its size.

[moi2388]

High luminosity large hadron collider

[cern]

They missed an opportunity to add 'Colossal' to the beginning, so the acronym would be supersymmetric -- the CHL-LHC

[onion2k]

Ho-Ly - LHC maybe.