diff --git a/core/main.mk b/core/main.mk
index 7553ede6be..014c0501e1 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -196,6 +196,9 @@ ifneq (,$(user_variant))
   ifeq ($(user_variant),userdebug)
     # Pick up some extra useful tools
     tags_to_install += debug
+
+    # Enable Dalvik lock contention logging for userdebug builds.
+    ADDITIONAL_BUILD_PROPERTIES += dalvik.vm.lockprof.threshold=500
   else
     # Disable debugging in plain user builds.
     enable_target_debugging :=