diff --git a/filesystem/android_device.go b/filesystem/android_device.go
index ae7755f..d341a0c 100644
--- a/filesystem/android_device.go
+++ b/filesystem/android_device.go
@@ -16,6 +16,7 @@
 
 import (
 	"strings"
+	"sync/atomic"
 
 	"android/soong/android"
 
@@ -79,6 +80,8 @@
 	return module
 }
 
+var numAutogeneratedAndroidDevicesOnceKey android.OnceKey = android.NewOnceKey("num_auto_generated_anroid_devices")
+
 type partitionDepTagType struct {
 	blueprint.BaseDependencyTag
 }
@@ -190,15 +193,34 @@
 
 	a.copyFilesToProductOut(ctx)
 
-	out := android.PathForModuleOut(ctx, "out")
+	allImagesStamp := android.PathForModuleOut(ctx, "all_images_stamp")
 	ctx.Build(pctx, android.BuildParams{
 		Rule:       android.Touch,
-		Output:     out,
+		Output:     allImagesStamp,
 		Implicits:  deps,
 		Validation: a.copyToProductOutTimestamp,
 	})
-	ctx.SetOutputFiles(android.Paths{out}, "")
-	ctx.CheckbuildFile(out)
+	ctx.SetOutputFiles(android.Paths{allImagesStamp}, "")
+	ctx.CheckbuildFile(allImagesStamp)
+
+	if ctx.OtherModuleIsAutoGenerated(ctx.Module()) {
+		numAutogeneratedAndroidDevices := ctx.Config().Once(numAutogeneratedAndroidDevicesOnceKey, func() interface{} {
+			return &atomic.Int32{}
+		}).(*atomic.Int32)
+		total := numAutogeneratedAndroidDevices.Add(1)
+		if total > 1 {
+			// There should only be 1 autogenerated android_device module. That one will be
+			// made the default thing to build in soong-only builds.
+			ctx.ModuleErrorf("There cannot be more than 1 autogenerated android_device module")
+		}
+	}
+
+	if !ctx.Config().KatiEnabled() && ctx.OtherModuleIsAutoGenerated(ctx.Module()) {
+		// In soong-only builds, build this module by default.
+		// This is the analogue to this make code:
+		// https://cs.android.com/android/platform/superproject/main/+/main:build/make/core/main.mk;l=1396;drc=6595459cdd8164a6008335f6372c9f97b9094060
+		ctx.Phony("droidcore-unbundled", allImagesStamp)
+	}
 }
 
 type targetFilesZipCopy struct {