diff --git a/core/clear_vars.mk b/core/clear_vars.mk
index 5effac7..019892e 100644
--- a/core/clear_vars.mk
+++ b/core/clear_vars.mk
@@ -277,6 +277,7 @@
 LOCAL_SOONG_BUNDLE :=
 LOCAL_SOONG_CLASSES_JAR :=
 LOCAL_SOONG_DEX_JAR :=
+LOCAL_SOONG_DEXPREOPT_CONFIG :=
 LOCAL_SOONG_EXPORT_PROGUARD_FLAGS :=
 LOCAL_SOONG_HEADER_JAR :=
 LOCAL_SOONG_JACOCO_REPORT_CLASSES_JAR :=
diff --git a/core/definitions.mk b/core/definitions.mk
index 4300efe..033ab30 100644
--- a/core/definitions.mk
+++ b/core/definitions.mk
@@ -632,14 +632,6 @@
 endef
 
 ###########################################################
-## Convert install path to on-device path.
-###########################################################
-# $(1): install path
-define install-path-to-on-device-path
-$(patsubst $(PRODUCT_OUT)%,%,$(1))
-endef
-
-###########################################################
 ## The intermediates directory.  Where object files go for
 ## a given target.  We could technically get away without
 ## the "_intermediates" suffix on the directory, but it's
diff --git a/core/dex_preopt_config_merger.py b/core/dex_preopt_config_merger.py
new file mode 100755
index 0000000..ebb99e1
--- /dev/null
+++ b/core/dex_preopt_config_merger.py
@@ -0,0 +1,100 @@
+#!/usr/bin/env python
+#
+# Copyright (C) 2021 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+"""
+A tool for merging dexpreopt.config files for <uses-library> dependencies into
+the dexpreopt.config file of the library/app that uses them. This is needed to
+generate class loader context (CLC) for dexpreopt.
+
+In Make there is no topological order when processing different modules, so a
+<uses-library> dependency module may have not been processed yet by the time the
+dependent module is processed. Therefore makefiles communicate the information
+from dependencies via dexpreopt.config files and add file-level dependencies
+from a module dexpreopt.config to its dependency configs. The actual patching
+of configs is done by this script, which is called from the makefiles.
+"""
+
+from __future__ import print_function
+
+import json
+from collections import OrderedDict
+import sys
+
+
+def main():
+  """Program entry point."""
+  if len(sys.argv) < 2:
+    raise SystemExit('usage: %s <main-config> [dep-config ...]' % sys.argv[0])
+
+  # Read all JSON configs.
+  cfgs = []
+  for arg in sys.argv[1:]:
+    with open(arg, 'r') as f:
+      cfgs.append(json.load(f, object_pairs_hook=OrderedDict))
+
+  # The first config is the dexpreopted library/app, the rest are its
+  # <uses-library> dependencies.
+  cfg0 = cfgs[0]
+
+  # Put dependency configs in a map keyed on module name (for easier lookup).
+  uses_libs = {}
+  for cfg in cfgs[1:]:
+    uses_libs[cfg['Name']] = cfg
+
+  # Load the original CLC map.
+  clc_map = cfg0['ClassLoaderContexts']
+
+  # Create a new CLC map that will be a copy of the original one with patched
+  # fields from dependency dexpreopt.config files.
+  clc_map2 = OrderedDict()
+
+  # Patch CLC for each SDK version. Although this should not be necessary for
+  # compatibility libraries (so-called "conditional CLC"), because they all have
+  # known names, known paths in system/framework, and no subcontext. But keep
+  # the loop in case this changes in the future.
+  for sdk_ver in clc_map:
+    clcs = clc_map[sdk_ver]
+    clcs2 = OrderedDict()
+    for lib in clcs:
+      clc = clcs[lib]
+      if lib in uses_libs:
+        ulib = uses_libs[lib]
+        # On-host (build) path to the dependency DEX jar file.
+        clc['Host'] = ulib['BuildPath']
+        # On-device (install) path to the dependency DEX jar file.
+        clc['Device'] = ulib['DexLocation']
+        # CLC of the dependency becomes a subcontext. We only need sub-CLC for
+        # 'any' version because all other versions are for compatibility
+        # libraries, which exist only for apps and not for libraries.
+        clc['Subcontexts'] = ulib['ClassLoaderContexts'].get('any')
+        # Patch the library name in the CLC as well.
+        clcs2[ulib['ProvidesUsesLibrary']] = clc
+      else:
+        # dexpreopt.config for this <uses-library> is not among the script
+        # arguments, which may be the case with compatibility libraries that
+        # don't need patching anyway. Just use the original CLC.
+        clcs2[lib] = clc
+    clc_map2[sdk_ver] = clcs2
+
+  # Overwrite the original class loader context with the patched one.
+  cfg0['ClassLoaderContexts'] = clc_map2
+
+  # Update dexpreopt.config file.
+  with open(sys.argv[1], 'w') as f:
+    f.write(json.dumps(cfgs[0], indent=4, separators=(',', ': ')))
+
+if __name__ == '__main__':
+  main()
diff --git a/core/dex_preopt_odex_install.mk b/core/dex_preopt_odex_install.mk
index b74e047..084b302 100644
--- a/core/dex_preopt_odex_install.mk
+++ b/core/dex_preopt_odex_install.mk
@@ -189,24 +189,28 @@
   my_filtered_optional_uses_libraries := $(filter-out $(INTERNAL_PLATFORM_MISSING_USES_LIBRARIES), \
     $(LOCAL_OPTIONAL_USES_LIBRARIES))
 
-  # compatibility libraries are added to class loader context of an app only if
-  # targetSdkVersion in the app's manifest is lower than the given SDK version
+  ifeq ($(LOCAL_MODULE_CLASS),APPS)
+    # compatibility libraries are added to class loader context of an app only if
+    # targetSdkVersion in the app's manifest is lower than the given SDK version
 
-  my_dexpreopt_libs_compat_28 := \
-    org.apache.http.legacy
+    my_dexpreopt_libs_compat_28 := \
+      org.apache.http.legacy
 
-  my_dexpreopt_libs_compat_29 := \
-    android.hidl.base-V1.0-java \
-    android.hidl.manager-V1.0-java
+    my_dexpreopt_libs_compat_29 := \
+      android.hidl.base-V1.0-java \
+      android.hidl.manager-V1.0-java
 
-  my_dexpreopt_libs_compat_30 := \
-    android.test.base \
-    android.test.mock
+    my_dexpreopt_libs_compat_30 := \
+      android.test.base \
+      android.test.mock
 
-  my_dexpreopt_libs_compat := \
-    $(my_dexpreopt_libs_compat_28) \
-    $(my_dexpreopt_libs_compat_29) \
-    $(my_dexpreopt_libs_compat_30)
+    my_dexpreopt_libs_compat := \
+      $(my_dexpreopt_libs_compat_28) \
+      $(my_dexpreopt_libs_compat_29) \
+      $(my_dexpreopt_libs_compat_30)
+  else
+    my_dexpreopt_libs_compat :=
+  endif
 
   my_dexpreopt_libs := $(sort \
     $(LOCAL_USES_LIBRARIES) \
@@ -215,13 +219,25 @@
 
   # 1: SDK version
   # 2: list of libraries
+  #
+  # Make does not process modules in topological order wrt. <uses-library>
+  # dependencies, therefore we cannot rely on variables to get the information
+  # about dependencies (in particular, their on-device path and class loader
+  # context). This information is communicated via dexpreopt.config files: each
+  # config depends on configs for <uses-library> dependencies of this module,
+  # and the dex_preopt_config_merger.py script reads all configs and inserts the
+  # missing bits from dependency configs into the module config.
+  #
+  # By default on-device path is /system/framework/*.jar, and class loader
+  # subcontext is empty. These values are correct for compatibility libraries,
+  # which are special and not handled by dex_preopt_config_merger.py.
+  #
   add_json_class_loader_context = \
     $(call add_json_map, $(1)) \
     $(foreach lib, $(2),\
       $(call add_json_map, $(lib)) \
-      $(eval file := $(filter %/$(lib).jar, $(call module-installed-files,$(lib)))) \
-      $(call add_json_str, Host,        $(call intermediates-dir-for,JAVA_LIBRARIES,$(lib),,COMMON)/javalib.jar) \
-      $(call add_json_str, Device,      $(call install-path-to-on-device-path,$(file))) \
+      $(call add_json_str, Host, $(call intermediates-dir-for,JAVA_LIBRARIES,$(lib),,COMMON)/javalib.jar) \
+      $(call add_json_str, Device, /system/framework/$(lib).jar) \
       $(call add_json_map, Subcontexts, ${$}) $(call end_json_map) \
       $(call end_json_map)) \
     $(call end_json_map)
@@ -275,12 +291,27 @@
   my_dexpreopt_config := $(intermediates)/dexpreopt.config
   my_dexpreopt_script := $(intermediates)/dexpreopt.sh
   my_dexpreopt_zip := $(intermediates)/dexpreopt.zip
+  my_dexpreopt_config_merger := $(BUILD_SYSTEM)/dex_preopt_config_merger.py
 
+  # Module dexpreopt.config depends on dexpreopt.config files of each
+  # <uses-library> dependency, because these libraries may be processed after
+  # the current module by Make (there's no topological order), so the dependency
+  # information (paths, class loader context) may not be ready yet by the time
+  # this dexpreopt.config is generated. So it's necessary to add file-level
+  # dependencies between dexpreopt.config files.
+  my_dexpreopt_dep_configs := $(foreach lib, \
+    $(filter-out $(my_dexpreopt_libs_compat),$(LOCAL_USES_LIBRARIES) $(my_filtered_optional_uses_libraries)), \
+    $(call intermediates-dir-for,JAVA_LIBRARIES,$(lib),,)/dexpreopt.config)
+
+  $(my_dexpreopt_config): $(my_dexpreopt_dep_configs) $(my_dexpreopt_config_merger)
   $(my_dexpreopt_config): PRIVATE_MODULE := $(LOCAL_MODULE)
   $(my_dexpreopt_config): PRIVATE_CONTENTS := $(json_contents)
+  $(my_dexpreopt_config): PRIVATE_DEP_CONFIGS := $(my_dexpreopt_dep_configs)
+  $(my_dexpreopt_config): PRIVATE_CONFIG_MERGER := $(my_dexpreopt_config_merger)
   $(my_dexpreopt_config):
 	@echo "$(PRIVATE_MODULE) dexpreopt.config"
 	echo -e -n '$(subst $(newline),\n,$(subst ','\'',$(subst \,\\,$(PRIVATE_CONTENTS))))' > $@
+	$(PRIVATE_CONFIG_MERGER) $@ $(PRIVATE_DEP_CONFIGS)
 
   .KATI_RESTAT: $(my_dexpreopt_script)
   $(my_dexpreopt_script): PRIVATE_MODULE := $(LOCAL_MODULE)
diff --git a/core/soong_java_prebuilt.mk b/core/soong_java_prebuilt.mk
index 5444d96..c600178 100644
--- a/core/soong_java_prebuilt.mk
+++ b/core/soong_java_prebuilt.mk
@@ -5,6 +5,7 @@
 # LOCAL_SOONG_HEADER_JAR
 # LOCAL_SOONG_DEX_JAR
 # LOCAL_SOONG_JACOCO_REPORT_CLASSES_JAR
+# LOCAL_SOONG_DEXPREOPT_CONFIG
 
 ifneq ($(LOCAL_MODULE_MAKEFILE),$(SOONG_ANDROID_MK))
   $(call pretty-error,soong_java_prebuilt.mk may only be used from Soong)
@@ -146,6 +147,12 @@
   ALL_MODULES.$(my_register_name).AAR := $(LOCAL_SOONG_AAR)
 endif
 
+# Copy dexpreopt.config files from Soong libraries to the location where Make
+# modules can find them.
+ifdef LOCAL_SOONG_DEXPREOPT_CONFIG
+  $(eval $(call copy-one-file,$(LOCAL_SOONG_DEXPREOPT_CONFIG), $(call local-intermediates-dir,)/dexpreopt.config))
+endif
+
 javac-check : $(full_classes_jar)
 javac-check-$(LOCAL_MODULE) : $(full_classes_jar)
 .PHONY: javac-check-$(LOCAL_MODULE)
diff --git a/tools/releasetools/Android.bp b/tools/releasetools/Android.bp
index 60378b8..0c84d4f 100644
--- a/tools/releasetools/Android.bp
+++ b/tools/releasetools/Android.bp
@@ -282,6 +282,7 @@
         "boot_signer",
         "brotli",
         "bsdiff",
+        "deapexer",
         "imgdiff",
         "minigzip",
         "lz4",