This is an open-label, multicenter, Phase I dose-escalation study to assess the safety, tolerability, and pharmacokinetics of GDC-0623 in patients with locally advanced or metastatic solid tumors. Patients will be enrolled in one of two stages: a dose-escalation stage (Stage I) followed by an expansion stage (Stage II). Stage I will evaluate the safety, tolerability, and pharmacokinetics of increasing doses of GDC-0623 administered orally on a 21 day on/7-day off dosing schedule.