In response to Michael Bishop: maybe you could use IP anonymization?
From the explanation:
When a customer of Analytics requests IP address anonymization, Analytics anonymizes the address as soon as technically feasible at the earliest possible stage of the collection network. The IP anonymization feature in Analytics sets the last octet of IPv4 user IP addresses and the last 80 bits of IPv6 addresses to zeros in memory shortly after being sent to the Analytics Collection Network. The full IP address is never written to disk in this case.