This open-label, multicenter, non-randomized, dose-escalating phase Ib study with an expansion cohort will determine the recommended Phase II dose and schedule to investigate safety, tolerability, and activity of RO5083945 in combination with cisplatin and gemcitabine or carboplatin and paclitaxel in patients with advanced or recurrent non-small cell lung cancer of squamous histology who have not received prior chemotherapy for the metastatic disease. Cohorts of patients will receive escalating doses of RO5083945 in combination with up to 6 cycles of cisplatin and gemcitabine or carboplatin and paclitaxel. Anticipated time on study treatment is until disease progression or unacceptable toxicity occurs.