diff --git a/core/base_rules.mk b/core/base_rules.mk
index c182a77..a6bf504 100644
--- a/core/base_rules.mk
+++ b/core/base_rules.mk
@@ -392,6 +392,25 @@
 
 endif # !LOCAL_UNINSTALLABLE_MODULE
 
+
+###########################################################
+## CHECK_BUILD goals
+###########################################################
+
+# If nobody has defined a more specific module for the
+# checked modules, use LOCAL_BUILT_MODULE.  This was old
+# behavior, so it should be a safe default.
+ifndef LOCAL_CHECKED_MODULE
+  LOCAL_CHECKED_MODULE := $(LOCAL_BUILT_MODULE)
+endif
+
+# If they request that this module not be checked, then don't.
+# PLEASE DON'T SET THIS.  ANY PLACES THAT SET THIS WITHOUT
+# GOOD REASON WILL HAVE IT REMOVED.
+ifdef LOCAL_DONT_CHECK_MODULE
+  LOCAL_CHECKED_MODULE :=
+endif
+
 ###########################################################
 ## Register with ALL_MODULES
 ###########################################################
@@ -404,6 +423,8 @@
     $(ALL_MODULES.$(LOCAL_MODULE).PATH) $(LOCAL_PATH)
 ALL_MODULES.$(LOCAL_MODULE).TAGS := \
     $(ALL_MODULES.$(LOCAL_MODULE).TAGS) $(LOCAL_MODULE_TAGS)
+ALL_MODULES.$(LOCAL_MODULE).CHECKED := \
+    $(ALL_MODULES.$(LOCAL_MODULE).CHECKED) $(LOCAL_CHECKED_MODULE)
 ALL_MODULES.$(LOCAL_MODULE).BUILT := \
     $(ALL_MODULES.$(LOCAL_MODULE).BUILT) $(LOCAL_BUILT_MODULE)
 ALL_MODULES.$(LOCAL_MODULE).INSTALLED := \
@@ -430,9 +451,6 @@
 $(foreach tag,$(LOCAL_MODULE_TAGS),\
     $(eval ALL_MODULE_NAME_TAGS.$(tag) += $(LOCAL_MODULE)))
 
-# Always build everything, but only install a subset.
-ALL_BUILT_MODULES += $(LOCAL_BUILT_MODULE)
-
 ###########################################################
 ## NOTICE files
 ###########################################################
diff --git a/core/clear_vars.mk b/core/clear_vars.mk
index b2e95b4..031bc0b 100644
--- a/core/clear_vars.mk
+++ b/core/clear_vars.mk
@@ -5,6 +5,8 @@
 LOCAL_MODULE:=
 LOCAL_MODULE_PATH:=
 LOCAL_MODULE_STEM:=
+LOCAL_DONT_CHECK_MODULE:=
+LOCAL_CHECKED_MODULE:=
 LOCAL_BUILT_MODULE:=
 LOCAL_BUILT_MODULE_STEM:=
 OVERRIDE_BUILT_MODULE_PATH:=
diff --git a/core/definitions.mk b/core/definitions.mk
index e66c6b8..c84cbd8 100644
--- a/core/definitions.mk
+++ b/core/definitions.mk
@@ -41,9 +41,6 @@
 # set of installed targets.
 ALL_DEFAULT_INSTALLED_MODULES:=
 
-# Full paths to all targets that will be built.
-ALL_BUILT_MODULES:=
-
 # The list of tags that have been defined by
 # LOCAL_MODULE_TAGS.  Each word in this variable maps
 # to a corresponding ALL_MODULE_TAGS.<tagname> variable
@@ -1239,21 +1236,21 @@
 $(hide) mkdir -p $(PRIVATE_CLASS_INTERMEDIATES_DIR)
 $(call unzip-jar-files,$(PRIVATE_STATIC_JAVA_LIBRARIES), \
     $(PRIVATE_CLASS_INTERMEDIATES_DIR))
-$(call dump-words-to-file,$(PRIVATE_JAVA_SOURCES),$(PRIVATE_INTERMEDIATES_DIR)/java-source-list)
+$(call dump-words-to-file,$(PRIVATE_JAVA_SOURCES),$(dir $(PRIVATE_CLASS_INTERMEDIATES_DIR))/java-source-list)
 $(hide) if [ -d "$(PRIVATE_SOURCE_INTERMEDIATES_DIR)" ]; then \
-	    find $(PRIVATE_SOURCE_INTERMEDIATES_DIR) -name '*.java' >> $(PRIVATE_INTERMEDIATES_DIR)/java-source-list; \
+	    find $(PRIVATE_SOURCE_INTERMEDIATES_DIR) -name '*.java' >> $(dir $(PRIVATE_CLASS_INTERMEDIATES_DIR))/java-source-list; \
 fi
-$(hide) tr ' ' '\n' < $(PRIVATE_INTERMEDIATES_DIR)/java-source-list \
-    | sort -u > $(PRIVATE_INTERMEDIATES_DIR)/java-source-list-uniq
+$(hide) tr ' ' '\n' < $(dir $(PRIVATE_CLASS_INTERMEDIATES_DIR))/java-source-list \
+    | sort -u > $(dir $(PRIVATE_CLASS_INTERMEDIATES_DIR))/java-source-list-uniq
 $(hide) $(TARGET_JAVAC) -encoding ascii $(PRIVATE_BOOTCLASSPATH) \
     $(addprefix -classpath ,$(strip \
         $(call normalize-path-list,$(PRIVATE_ALL_JAVA_LIBRARIES)))) \
     $(strip $(PRIVATE_JAVAC_DEBUG_FLAGS)) $(xlint_unchecked) \
     -extdirs "" -d $(PRIVATE_CLASS_INTERMEDIATES_DIR) \
-    \@$(PRIVATE_INTERMEDIATES_DIR)/java-source-list-uniq \
+    \@$(dir $(PRIVATE_CLASS_INTERMEDIATES_DIR))/java-source-list-uniq \
     || ( rm -rf $(PRIVATE_CLASS_INTERMEDIATES_DIR) ; exit 41 )
-$(hide) rm -f $(PRIVATE_INTERMEDIATES_DIR)/java-source-list
-$(hide) rm -f $(PRIVATE_INTERMEDIATES_DIR)/java-source-list-uniq
+$(hide) rm -f $(dir $(PRIVATE_CLASS_INTERMEDIATES_DIR))/java-source-list
+$(hide) rm -f $(dir $(PRIVATE_CLASS_INTERMEDIATES_DIR))/java-source-list-uniq
 $(hide) mkdir -p $(dir $@)
 $(hide) jar $(if $(strip $(PRIVATE_JAR_MANIFEST)),-cfm,-cf) \
     $@ $(PRIVATE_JAR_MANIFEST) -C $(PRIVATE_CLASS_INTERMEDIATES_DIR) .
diff --git a/core/java.mk b/core/java.mk
index 5a434c4..658b173 100644
--- a/core/java.mk
+++ b/core/java.mk
@@ -37,6 +37,54 @@
 $(error LOCAL_BUILT_MODULE_STEM may not be "$(LOCAL_BUILT_MODULE_STEM)")
 endif
 
+
+##############################################################################
+# Define the intermediate targets before including base_rules so they get
+# the correct environment.
+##############################################################################
+
+intermediates := $(call local-intermediates-dir)
+intermediates.COMMON := $(call local-intermediates-dir,COMMON)
+
+# This is cleared below, and re-set if we really need it.
+full_classes_jar := $(intermediates.COMMON)/classes.jar
+
+# Emma source code coverage
+ifneq ($(EMMA_INSTRUMENT),true)
+LOCAL_NO_EMMA_INSTRUMENT := true
+LOCAL_NO_EMMA_COMPILE := true
+endif
+
+# Choose leaf name for the compiled jar file.
+ifneq ($(LOCAL_NO_EMMA_COMPILE),true)
+full_classes_compiled_jar_leaf := classes-no-debug-var.jar
+else
+full_classes_compiled_jar_leaf := classes-full-debug.jar
+endif
+full_classes_compiled_jar := $(intermediates.COMMON)/$(full_classes_compiled_jar_leaf)
+
+emma_intermediates_dir := $(intermediates.COMMON)/emma_out
+# the 'lib/$(full_classes_compiled_jar_leaf)' portion of this path is fixed in
+# the emma tool
+full_classes_emma_jar := $(emma_intermediates_dir)/lib/$(full_classes_compiled_jar_leaf)
+full_classes_stubs_jar := $(intermediates.COMMON)/stubs.jar
+full_classes_jarjar_jar := $(full_classes_jar)
+built_dex := $(intermediates.COMMON)/classes.dex
+
+LOCAL_INTERMEDIATE_TARGETS += \
+    $(full_classes_jar) \
+    $(full_classes_compiled_jar) \
+    $(full_classes_emma_jar) \
+    $(full_classes_stubs_jar) \
+    $(full_classes_jarjar_jar) \
+    $(built_dex)
+
+
+# TODO: It looks like the only thing we need from base_rules is
+# all_java_sources.  See if we can get that by adding a
+# common_java.mk, and moving the include of base_rules.mk to
+# after all the declarations.
+
 #######################################
 include $(BUILD_SYSTEM)/base_rules.mk
 #######################################
@@ -65,6 +113,7 @@
 # LOCAL_BUILT_MODULE, so it will inherit the necessary PRIVATE_*
 # variable definitions.
 full_classes_jar := $(intermediates.COMMON)/classes.jar
+built_dex := $(intermediates.COMMON)/classes.dex
 
 # Droiddoc isn't currently able to generate stubs for modules, so we're just
 # allowing it to use the classes.jar as the "stubs" that would be use to link
@@ -74,34 +123,28 @@
 #   it, so it's closest to what's on the device.
 # - This extra copy, with the dependency on LOCAL_BUILT_MODULE allows the
 #   PRIVATE_ vars to be preserved.
-full_classes_stubs_jar := $(intermediates.COMMON)/stubs.jar
 $(full_classes_stubs_jar): PRIVATE_SOURCE_FILE := $(full_classes_jar)
 $(full_classes_stubs_jar) : $(LOCAL_BUILT_MODULE) | $(ACP)
 	@echo Copying $(PRIVATE_SOURCE_FILE)
 	$(hide) $(ACP) -fp $(PRIVATE_SOURCE_FILE) $@
 ALL_MODULES.$(LOCAL_MODULE).STUBS := $(full_classes_stubs_jar)
 
-# Emma source code coverage
-ifneq ($(EMMA_INSTRUMENT),true) 
-LOCAL_NO_EMMA_INSTRUMENT := true
-LOCAL_NO_EMMA_COMPILE := true
-endif
-
-# Choose leaf name for the compiled jar file.
-ifneq ($(LOCAL_NO_EMMA_COMPILE),true) 
-full_classes_compiled_jar_leaf := classes-no-debug-var.jar
-else
-full_classes_compiled_jar_leaf := classes-full-debug.jar
-endif
-
 # Compile the java files to a .jar file.
 # This intentionally depends on java_sources, not all_java_sources.
 # Deps for generated source files must be handled separately,
 # via deps on the target that generates the sources.
-full_classes_compiled_jar := $(intermediates.COMMON)/$(full_classes_compiled_jar_leaf)
 $(full_classes_compiled_jar): $(java_sources) $(full_java_lib_deps)
 	$(transform-java-to-classes.jar)
 
+# All of the rules after full_classes_compiled_jar are very unlikely
+# to fail except for bugs in their respective tools.  If you would
+# like to run these rules, add the "all" modifier goal to the make
+# command line.
+# This overwrites the value defined in base_rules.mk.  That's a little
+# dirty.  It's preferable to set LOCAL_CHECKED_MODULE, but this has to
+# be done after the inclusion of base_rules.mk.
+ALL_MODULES.$(LOCAL_MODULE).CHECKED := $(full_classes_compiled_jar)
+
 ifneq ($(LOCAL_NO_EMMA_COMPILE),true) 
 # If you instrument class files that have local variable debug information in
 # them emma does not correctly maintain the local variable table.
@@ -115,11 +158,6 @@
 $(full_classes_compiled_jar): PRIVATE_JAVAC_DEBUG_FLAGS := -g
 endif
 
-emma_intermediates_dir := $(intermediates.COMMON)/emma_out
-# the 'lib/$(full_classes_compiled_jar_leaf)' portion of this path is fixed in 
-# the emma tool
-full_classes_emma_jar := $(emma_intermediates_dir)/lib/$(full_classes_compiled_jar_leaf)
-
 ifeq ($(LOCAL_IS_STATIC_JAVA_LIBRARY),true)
 # Skip adding emma instrumentation to class files if this is a static library,
 # since it will be instrumented by the package that includes it
@@ -142,7 +180,6 @@
 
 # Run jarjar if necessary, otherwise just copy the file.  This is the last
 # part of this step, so the output of this command is full_classes_jar.
-full_classes_jarjar_jar := $(full_classes_jar)
 ifneq ($(strip $(LOCAL_JARJAR_RULES)),)
 $(full_classes_jarjar_jar): PRIVATE_JARJAR_RULES := $(LOCAL_JARJAR_RULES)
 $(full_classes_jarjar_jar): $(full_classes_emma_jar) | jarjar
@@ -154,9 +191,6 @@
 	$(hide) $(ACP) $< $@
 endif
 
-
-built_dex := $(intermediates.COMMON)/classes.dex
-
 # Override PRIVATE_INTERMEDIATES_DIR so that install-dex-debug
 # will work even when intermediates != intermediates.COMMON.
 $(built_dex): PRIVATE_INTERMEDIATES_DIR := $(intermediates.COMMON)
diff --git a/core/main.mk b/core/main.mk
index fb1a58f..2c7bb78 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -126,7 +126,7 @@
 # These are the modifier targets that don't do anything themselves, but
 # change the behavior of the build.
 # (must be defined before including definitions.make)
-INTERNAL_MODIFIER_TARGETS := showcommands
+INTERNAL_MODIFIER_TARGETS := showcommands checkbuild
 
 # Bring in standard build system definitions.
 include $(BUILD_SYSTEM)/definitions.mk
@@ -292,11 +292,11 @@
 endif
 
 
-# If all they typed was make showcommands, we'll actually build
-# the default target.
-ifeq ($(MAKECMDGOALS),showcommands)
-.PHONY: showcommands
-showcommands: $(DEFAULT_GOAL)
+# If they only used the modifier goals (showcommands, checkbuild), we'll actually
+# build the default target.
+ifeq ($(filter-out $(INTERNAL_MODIFIER_TARGETS),$(MAKECMDGOALS)),)
+.PHONY: $(INTERNAL_MODIFIER_TARGETS)
+$(INTERNAL_MODIFIER_TARGETS): $(DEFAULT_GOAL)
 endif
 
 # These targets are going to delete stuff, don't bother including
@@ -530,7 +530,6 @@
 # poisons the rest of the tags and shouldn't appear
 # on any list.
 Default_MODULES := $(sort $(ALL_DEFAULT_INSTALLED_MODULES) \
-                          $(ALL_BUILT_MODULES) \
                           $(CUSTOM_MODULES))
 # TODO: Remove the 3 places in the tree that use
 # ALL_DEFAULT_INSTALLED_MODULES and get rid of it from this list.
@@ -596,7 +595,7 @@
 endif
 
 
-# config/Makefile contains extra stuff that we don't want to pollute this
+# build/core/Makefile contains extra stuff that we don't want to pollute this
 # top-level makefile with.  It expects that ALL_DEFAULT_INSTALLED_MODULES
 # contains everything that's built during the current make, but it also further
 # extends ALL_DEFAULT_INSTALLED_MODULES.
@@ -607,6 +606,20 @@
 
 endif # dont_bother
 
+# These are additional goals that we build, in order to make sure that there
+# is as little code as possible in the tree that doesn't build.
+modules_to_check := $(foreach m,$(ALL_MODULES),$(ALL_MODULES.$(m).CHECKED))
+
+# If you would like to build all goals, and not skip any intermediate
+# steps, you can pass the "all" modifier goal on the commandline.
+ifneq ($(filter all,$(MAKECMDGOALS)),)
+modules_to_check += $(foreach m,$(ALL_MODULES),$(ALL_MODULES.$(m).BUILT))
+endif
+
+# for easier debugging
+modules_to_check := $(sort $(modules_to_check))
+#$(error modules_to_check $(modules_to_check))
+
 # -------------------------------------------------------------------
 # This is used to to get the ordering right, you can also use these,
 # but they're considered undocumented, so don't complain if their
@@ -624,10 +637,16 @@
 
 # All the droid stuff, in directories
 .PHONY: files
-files: prebuilt $(modules_to_install) $(INSTALLED_ANDROID_INFO_TXT_TARGET)
+files: prebuilt \
+        $(modules_to_install) \
+        $(modules_to_check) \
+        $(INSTALLED_ANDROID_INFO_TXT_TARGET)
 
 # -------------------------------------------------------------------
 
+.PHONY: checkbuild
+checkbuild: $(modules_to_check)
+
 .PHONY: ramdisk
 ramdisk: $(INSTALLED_RAMDISK_TARGET)