diff --git a/core/config.mk b/core/config.mk
index f839d3d..dba2555 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -499,6 +499,11 @@
 
 USE_PREBUILT_SDK_TOOLS_IN_PLACE := true
 
+# TODO(ccross): remove this once the build server no longer references it
+ifdef DX_ALT_JAR
+DX_JAR := DX_ALT_JAR
+endif
+
 #
 # Tools that are prebuilts for TARGET_BUILD_APPS
 #
@@ -506,24 +511,16 @@
   AIDL := $(HOST_OUT_EXECUTABLES)/aidl
   AAPT := $(HOST_OUT_EXECUTABLES)/aapt
   AAPT2 := $(HOST_OUT_EXECUTABLES)/aapt2
+  DX_JAR ?= $(HOST_OUT_JAVA_LIBRARIES)/dx.jar
   MAINDEXCLASSES := $(HOST_OUT_EXECUTABLES)/mainDexClasses
   SIGNAPK_JAR := $(HOST_OUT_JAVA_LIBRARIES)/signapk$(COMMON_JAVA_PACKAGE_SUFFIX)
   SIGNAPK_JNI_LIBRARY_PATH := $(HOST_OUT_SHARED_LIBRARIES)
   ZIPALIGN := $(HOST_OUT_EXECUTABLES)/zipalign
-
-  ifndef DX_ALT_JAR
-    DX := $(HOST_OUT_EXECUTABLES)/dx
-    DX_COMMAND := $(DX) -JXms16M -JXmx2048M
-  else
-    DX := $(DX_ALT_JAR)
-    DX_COMMAND := $(JAVA) -Xms16M -Xmx2048M -jar $(DX)
-  endif
 else # TARGET_BUILD_APPS || TARGET_BUILD_PDK
   AIDL := $(prebuilt_sdk_tools_bin)/aidl
   AAPT := $(prebuilt_sdk_tools_bin)/aapt
   AAPT2 := $(prebuilt_sdk_tools_bin)/aapt2
-  DX := $(prebuilt_sdk_tools)/dx
-  DX_COMMAND := $(DX) -JXms16M -JXmx2048M
+  DX_JAR ?= $(prebuilt_sdk_tools)/lib/dx.jar
   MAINDEXCLASSES := $(prebuilt_sdk_tools)/mainDexClasses
   ZIPALIGN := $(prebuilt_sdk_tools_bin)/zipalign
   SIGNAPK_JAR := $(prebuilt_sdk_tools)/lib/signapk$(COMMON_JAVA_PACKAGE_SUFFIX)
@@ -561,6 +558,16 @@
 ZIP2ZIP := $(SOONG_HOST_OUT_EXECUTABLES)/zip2zip
 ZIPTIME := $(prebuilt_build_tools_bin)/ziptime
 
+# DX can be overriden on the command line
+ifndef DX
+#TODO: use a smaller -Xmx value for most libraries;
+#      only core.jar and framework.jar need a heap this big.
+DX := $(JAVA) -Xms16M -Xmx2048M -jar $(DX_JAR)
+DX_DEPS := $(DX_JAR)
+else
+DX_DEPS ?= $(DX)
+endif
+
 # ---------------------------------------------------------------
 # Generic tools.
 JACK := $(HOST_OUT_EXECUTABLES)/jack
diff --git a/core/definitions.mk b/core/definitions.mk
index fe8d644..d0f6d4c 100644
--- a/core/definitions.mk
+++ b/core/definitions.mk
@@ -2557,7 +2557,7 @@
 @echo "target Dex: $(PRIVATE_MODULE)"
 @mkdir -p $(dir $@)
 $(hide) rm -f $(dir $@)classes*.dex
-$(hide) $(DX_COMMAND) \
+$(hide) $(DX) \
     --dex --output=$(dir $@) \
     --min-sdk-version=$(call codename-or-sdk-to-sdk,$(PRIVATE_DEFAULT_APP_TARGET_SDK)) \
     $(if $(NO_OPTIMIZE_DX), \
diff --git a/core/host_dalvik_java_library.mk b/core/host_dalvik_java_library.mk
index 4f3069f..94ce5b3 100644
--- a/core/host_dalvik_java_library.mk
+++ b/core/host_dalvik_java_library.mk
@@ -136,7 +136,7 @@
 else # !LOCAL_IS_STATIC_JAVA_LIBRARY
 $(built_dex): PRIVATE_INTERMEDIATES_DIR := $(intermediates.COMMON)
 $(built_dex): PRIVATE_DX_FLAGS := $(LOCAL_DX_FLAGS)
-$(built_dex): $(full_classes_jar) $(DX)
+$(built_dex): $(full_classes_jar) $(DX_DEPS)
 	$(transform-classes.jar-to-dex)
 
 $(LOCAL_BUILT_MODULE): PRIVATE_DEX_FILE := $(built_dex)
diff --git a/core/java.mk b/core/java.mk
index e456993..24080dc 100644
--- a/core/java.mk
+++ b/core/java.mk
@@ -673,7 +673,7 @@
 ifeq ($(LOCAL_EMMA_INSTRUMENT),true)
 $(built_dex_intermediate): PRIVATE_DX_FLAGS += --no-locals
 endif
-$(built_dex_intermediate): $(full_classes_jar) $(DX)
+$(built_dex_intermediate): $(full_classes_jar) $(DX_DEPS)
 	$(transform-classes.jar-to-dex)
 endif # LOCAL_JACK_ENABLED is disabled