If the primary function of the LLC is *not* renting out property, then the sub-lease is included on the SCH C. For example, if you own a bait & tackle business that sells product and services, that is of course reported on SCH C. If your business pays rent for it's operating location, that is a SCH C business expense. If your business sub-lets a part of the building it pays rent for, then that rental income is reported on SCH C. Nothing needs to be reported on SCH E.
If the business owns the building, then you already claim the mortgage interest on SCH C and you already depreciate the building over 39 years. Nothing needs to change on that front. The rental income is basically included as "a part of" your regular business income.
The business will continue to deduct other business expenses such as utilities as normal, since most likely there is no separate metering between the building you rent or own, and the section of that building you sub-let out. There's also no change in how you report/claim property taxes or insurance.
