diff --git a/tools/aapt/Android.mk b/tools/aapt/Android.mk
index 499a7ac..b339a2c 100644
--- a/tools/aapt/Android.mk
+++ b/tools/aapt/Android.mk
@@ -4,6 +4,9 @@
 # Android Asset Packaging Tool
 #
 
+# This tool is prebuilt if we're doing an app-only build.
+ifeq ($(TARGET_BUILD_APPS),)
+
 LOCAL_PATH:= $(call my-dir)
 include $(CLEAR_VARS)
 
@@ -53,3 +56,4 @@
 
 include $(BUILD_HOST_EXECUTABLE)
 
+endif # TARGET_BUILD_APPS
diff --git a/tools/aidl/Android.mk b/tools/aidl/Android.mk
index 944aeb6..2ad0728 100644
--- a/tools/aidl/Android.mk
+++ b/tools/aidl/Android.mk
@@ -2,6 +2,9 @@
 #
 # Copies files into the directory structure described by a manifest
 
+# This tool is prebuilt if we're doing an app-only build.
+ifeq ($(TARGET_BUILD_APPS),)
+
 LOCAL_PATH:= $(call my-dir)
 include $(CLEAR_VARS)
 
@@ -21,4 +24,4 @@
 
 include $(BUILD_HOST_EXECUTABLE)
 
-
+endif # TARGET_BUILD_APPS