diff --git a/core/Makefile b/core/Makefile
index ac8b2f2..a23cdd4 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -1781,7 +1781,7 @@
 
 ifdef INSTALLED_DTBOIMAGE_TARGET
 INTERNAL_AVB_MAKE_VBMETA_IMAGE_ARGS += \
-		--include_descriptors_from_image $(INSTALLED_DTBOIMAGE_TARGET)
+    --include_descriptors_from_image $(INSTALLED_DTBOIMAGE_TARGET)
 endif
 
 ifeq ($(BOARD_BUILD_SYSTEM_ROOT_IMAGE),true)
@@ -2234,10 +2234,7 @@
 ifeq ($(BOARD_AVB_ENABLE),true)
 	$(hide) echo "board_avb_enable=true" >> $(zip_root)/META/misc_info.txt
 	$(hide) echo "board_avb_rollback_index=$(BOARD_AVB_ROLLBACK_INDEX)" >> $(zip_root)/META/misc_info.txt
-	$(hide) echo "board_avb_key_path=$(BOARD_AVB_KEY_PATH)" >> $(zip_root)/META/misc_info.txt
-	$(hide) echo "board_avb_algorithm=$(BOARD_AVB_ALGORITHM)" >> $(zip_root)/META/misc_info.txt
 	$(hide) echo "board_avb_boot_add_hash_footer_args=$(BOARD_AVB_BOOT_ADD_HASH_FOOTER_ARGS)" >> $(zip_root)/META/misc_info.txt
-	$(hide) echo "board_avb_system_add_hashtree_footer_args=$(BOARD_AVB_SYSTEM_ADD_HASHTREE_FOOTER_ARGS)" >> $(zip_root)/META/misc_info.txt
 	$(hide) echo "board_avb_make_vbmeta_image_args=$(BOARD_AVB_MAKE_VBMETA_IMAGE_ARGS)" >> $(zip_root)/META/misc_info.txt
 endif
 ifdef BOARD_BPT_INPUT_FILES
@@ -2292,8 +2289,14 @@
 	$(hide) cp $(INSTALLED_VENDORIMAGE_TARGET) $(zip_root)/IMAGES/
 endif
 ifdef BOARD_PREBUILT_DTBOIMAGE
-	$(hide) mkdir -p $(zip_root)/IMAGES
-	$(hide) cp $(INSTALLED_DTBOIMAGE_TARGET) $(zip_root)/IMAGES/
+	$(hide) mkdir -p $(zip_root)/PREBUILT_IMAGES
+	$(hide) cp $(INSTALLED_DTBOIMAGE_TARGET) $(zip_root)/PREBUILT_IMAGES/
+	$(hide) echo "has_dtbo=true" >> $(zip_root)/META/misc_info.txt
+ifeq ($(BOARD_AVB_ENABLE),true)
+	$(hide) echo "dtbo_size=$(BOARD_DTBOIMG_PARTITION_SIZE)" >> $(zip_root)/META/misc_info.txt
+	$(hide) echo "board_avb_dtbo_add_hash_footer_args=$(BOARD_AVB_DTBO_ADD_HASH_FOOTER_ARGS)" \
+	    >> $(zip_root)/META/misc_info.txt
+endif
 endif
 	@# Run fs_config on all the system, vendor, boot ramdisk,
 	@# and recovery ramdisk files in the zip, and save the output
diff --git a/core/clang/versions.mk b/core/clang/versions.mk
index c5cc690..c2473cd 100644
--- a/core/clang/versions.mk
+++ b/core/clang/versions.mk
@@ -1,4 +1,4 @@
 ## Clang/LLVM release versions.
 
-LLVM_PREBUILTS_VERSION ?= clang-3859424
+LLVM_PREBUILTS_VERSION ?= clang-4053586
 LLVM_PREBUILTS_BASE ?= prebuilts/clang/host
diff --git a/tools/releasetools/add_img_to_target_files.py b/tools/releasetools/add_img_to_target_files.py
index 86354e7..1d8090a 100755
--- a/tools/releasetools/add_img_to_target_files.py
+++ b/tools/releasetools/add_img_to_target_files.py
@@ -173,13 +173,43 @@
               block_list=block_list)
   return img.name
 
-def FindDtboPrebuilt(prefix="IMAGES/"):
-  """Find the prebuilt image of DTBO partition."""
 
-  prebuilt_path = os.path.join(OPTIONS.input_tmp, prefix, "dtbo.img")
-  if os.path.exists(prebuilt_path):
-    return prebuilt_path
-  return None
+def AddDtbo(output_zip, prefix="IMAGES/"):
+  """Adds the DTBO image.
+
+  Uses the image under prefix if it already exists. Otherwise looks for the
+  image under PREBUILT_IMAGES/, signs it as needed, and returns the image name.
+  """
+
+  img = OutputFile(output_zip, OPTIONS.input_tmp, prefix, "dtbo.img")
+  if os.path.exists(img.input_name):
+    print("dtbo.img already exists in %s, no need to rebuild..." % (prefix,))
+    return img.input_name
+
+  dtbo_prebuilt_path = os.path.join(
+      OPTIONS.input_tmp, "PREBUILT_IMAGES", "dtbo.img")
+  assert os.path.exists(dtbo_prebuilt_path)
+  shutil.copy(dtbo_prebuilt_path, img.name)
+
+  # AVB-sign the image as needed.
+  if OPTIONS.info_dict.get("board_avb_enable") == "true":
+    avbtool = os.getenv('AVBTOOL') or OPTIONS.info_dict["avb_avbtool"]
+    part_size = OPTIONS.info_dict["dtbo_size"]
+    # The AVB hash footer will be replaced if already present.
+    cmd = [avbtool, "add_hash_footer", "--image", img.name,
+           "--partition_size", str(part_size), "--partition_name", "dtbo"]
+    cmd.extend(shlex.split(OPTIONS.info_dict["avb_signing_args"]))
+    args = OPTIONS.info_dict.get("board_avb_dtbo_add_hash_footer_args")
+    if args and args.strip():
+      cmd.extend(shlex.split(args))
+    p = common.Run(cmd, stdout=subprocess.PIPE)
+    p.communicate()
+    assert p.returncode == 0, \
+        "avbtool add_hash_footer of %s failed" % (img.name,)
+
+  img.Write()
+  return img.name
+
 
 def CreateImage(input_dir, info_dict, what, output_file, block_list=None):
   print("creating " + what + ".img...")
@@ -308,7 +338,7 @@
               dtbo_img_path, prefix="IMAGES/"):
   """Create a VBMeta image and store it in output_zip."""
   img = OutputFile(output_zip, OPTIONS.input_tmp, prefix, "vbmeta.img")
-  avbtool = os.getenv('AVBTOOL') or "avbtool"
+  avbtool = os.getenv('AVBTOOL') or OPTIONS.info_dict["avb_avbtool"]
   cmd = [avbtool, "make_vbmeta_image",
          "--output", img.name,
          "--include_descriptors_from_image", boot_img_path,
@@ -317,10 +347,10 @@
     cmd.extend(["--include_descriptors_from_image", vendor_img_path])
   if dtbo_img_path is not None:
     cmd.extend(["--include_descriptors_from_image", dtbo_img_path])
-  if OPTIONS.info_dict.get("system_root_image", None) == "true":
+  if OPTIONS.info_dict.get("system_root_image") == "true":
     cmd.extend(["--setup_rootfs_from_kernel", system_img_path])
-  common.AppendAVBSigningArgs(cmd)
-  args = OPTIONS.info_dict.get("board_avb_make_vbmeta_image_args", None)
+  cmd.extend(shlex.split(OPTIONS.info_dict["avb_signing_args"]))
+  args = OPTIONS.info_dict.get("board_avb_make_vbmeta_image_args")
   if args and args.strip():
     cmd.extend(shlex.split(args))
   p = common.Run(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
@@ -500,7 +530,7 @@
 
   banner("system")
   system_img_path = AddSystem(
-    output_zip, recovery_img=recovery_image, boot_img=boot_image)
+      output_zip, recovery_img=recovery_image, boot_img=boot_image)
   vendor_img_path = None
   if has_vendor:
     banner("vendor")
@@ -513,13 +543,19 @@
     AddUserdata(output_zip)
     banner("cache")
     AddCache(output_zip)
-  if OPTIONS.info_dict.get("board_bpt_enable", None) == "true":
+
+  if OPTIONS.info_dict.get("board_bpt_enable") == "true":
     banner("partition-table")
     AddPartitionTable(output_zip)
-  if OPTIONS.info_dict.get("board_avb_enable", None) == "true":
+
+  dtbo_img_path = None
+  if OPTIONS.info_dict.get("has_dtbo") == "true":
+    banner("dtbo")
+    dtbo_img_path = AddDtbo(output_zip)
+
+  if OPTIONS.info_dict.get("board_avb_enable") == "true":
     banner("vbmeta")
     boot_contents = boot_image.WriteToTemp()
-    dtbo_img_path = FindDtboPrebuilt()
     AddVBMeta(output_zip, boot_contents.name, system_img_path,
               vendor_img_path, dtbo_img_path)
 
diff --git a/tools/releasetools/common.py b/tools/releasetools/common.py
index c022d24..652fadf 100644
--- a/tools/releasetools/common.py
+++ b/tools/releasetools/common.py
@@ -345,16 +345,6 @@
     print("%-25s = (%s) %s" % (k, type(v).__name__, v))
 
 
-def AppendAVBSigningArgs(cmd):
-  """Append signing arguments for avbtool."""
-  keypath = OPTIONS.info_dict.get("board_avb_key_path", None)
-  algorithm = OPTIONS.info_dict.get("board_avb_algorithm", None)
-  if not keypath or not algorithm:
-    algorithm = "SHA256_RSA4096"
-    keypath = "external/avb/test/data/testkey_rsa4096.pem"
-  cmd.extend(["--key", keypath, "--algorithm", algorithm])
-
-
 def _BuildBootableImage(sourcedir, fs_config_file, info_dict=None,
                         has_ramdisk=False, two_step_image=False):
   """Build a bootable image from the specified sourcedir.
@@ -491,12 +481,12 @@
 
   # AVB: if enabled, calculate and add hash to boot.img.
   if info_dict.get("board_avb_enable", None) == "true":
-    avbtool = os.getenv('AVBTOOL') or OPTIONS.info_dict["avb_avbtool"]
-    part_size = info_dict.get("boot_size", None)
+    avbtool = os.getenv('AVBTOOL') or info_dict["avb_avbtool"]
+    part_size = info_dict["boot_size"]
     cmd = [avbtool, "add_hash_footer", "--image", img.name,
            "--partition_size", str(part_size), "--partition_name", "boot"]
-    AppendAVBSigningArgs(cmd)
-    args = info_dict.get("board_avb_boot_add_hash_footer_args", None)
+    cmd.extend(shlex.split(info_dict["avb_signing_args"]))
+    args = info_dict.get("board_avb_boot_add_hash_footer_args")
     if args and args.strip():
       cmd.extend(shlex.split(args))
     p = Run(cmd, stdout=subprocess.PIPE)
diff --git a/tools/releasetools/edify_generator.py b/tools/releasetools/edify_generator.py
index 7883fe6..0c44faf 100644
--- a/tools/releasetools/edify_generator.py
+++ b/tools/releasetools/edify_generator.py
@@ -130,7 +130,7 @@
            '    getprop("ro.build.thumbprint") == "{tp}" ||\n'
            '    abort("Package expects build fingerprint of {fp} or '
            'thumbprint of {tp}; this device has a fingerprint of " '
-           '+ getprop("ro.build.fingerprint") and a thumbprint of " '
+           '+ getprop("ro.build.fingerprint") + " and a thumbprint of " '
            '+ getprop("ro.build.thumbprint") + ".");').format(fp=fp, tp=tp)
     self.script.append(cmd)