As you might know the protons the LHC is circulating are accelerated in various stages. From a duoplasmatron, they are first injected into a linear accelerator (up to 50 MeV), then in the first small circular accelerator, the Proton Synchroton Booster (50 MeV -> 1.4 GeV), then in the Proton Synchroton (1.4 GeV -> 26GeV) and then in the Super Proton Synchroton (26 GeV -> 450 GeV). Only after this are they injected into the LHC tunnel for the real kick (450 GeV -> 7 TeV).
But where do the protons come from? Rather banally, out of a bottle of hydrogen:
I find it amazing, the contrast between that hydrogen bottle and the mighty LHC complex necessary to accelerate the protons.