LLCs are not required to have bylaws. However, they are governed by an operating agreement which is like a corporation's bylaws.
California law requires that each corporation must have a president, a secretary, and a chief financial officer.
The authorized number of directors must be set out in the bylaws (or the articles). A corporation must have at least three directors unless the corporation has fewer than three shareholders. In that case, the number of its directors can be no less than the number of shareholders.
By-laws may be used to set principles for decision-making and to provide for specific rules and regulations, accompanied by offences and penalty clauses. By-laws can also set procedures for the application of authorisations and approvals from the municipality, for example.
Although organizations don't need to file these bylaws with the state, California law requires that the treasurer or other designated member of the organization maintains a copy on file.
There's also the fact that if you don't list the number of directors in your Articles of Incorporation, you're legally required to list that information in your bylaws (see California Corp Code § 212). The bottom line: corporate bylaws are not legally required, but they're pretty much essential for your corporation.