The two-day meet, an Olympic test event at Sochi's Sanki track that ends Sunday with the team relay, featured above-freezing temperatures and steady rain.
Langenhan, the reigning world silver medalist, finished his two runs with a combined time of 1 minute, 47.335 seconds, just 0.004 seconds ahead of Russia's Albert Demchenko. David Moeller of Germany was third.
Loch, the current world and Olympic champion, finished only sixth in the meet, but that was enough to claim the overall World Cup title. Langenhan and Moeller were second and third.
Josef Fendt, head of the international luge federation, said Sunday that the test event left observers happy with the track's safety and ice condition.
In the team relay, which will be an Olympic event for the first time at Sochi next year, Langenhan joined Tatjana Huefner, Tobias Wendl and Tobias Arlt, who had won gold in the women's and men's doubles competition Saturday, to win in 2:51.553, ahead of the Russian team by 0.156 seconds. Canada was third.
Germany also won the team relay overall World Cup, with Italy in second place and the United States third.