diff --git a/core/Makefile b/core/Makefile
index 2177a18..b08ad1b 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -1510,10 +1510,14 @@
 name := $(name)-symbols-$(FILE_NAME_TAG)
 
 SYMBOLS_ZIP := $(PRODUCT_OUT)/$(name).zip
+# For apps_only build we'll establish the dependency later in build/core/main.mk.
+ifndef TARGET_BUILD_APPS
 $(SYMBOLS_ZIP): $(INSTALLED_SYSTEMIMAGE) $(INSTALLED_BOOTIMAGE_TARGET)
+endif
+$(SYMBOLS_ZIP):
 	@echo "Package symbols: $@"
 	$(hide) rm -rf $@
-	$(hide) mkdir -p $(dir $@)
+	$(hide) mkdir -p $(dir $@) $(TARGET_OUT_UNSTRIPPED)
 	$(hide) zip -qr $@ $(TARGET_OUT_UNSTRIPPED)
 
 # -----------------------------------------------------------------
diff --git a/core/main.mk b/core/main.mk
index 749929a..9d6e233 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -936,6 +936,9 @@
   $(PROGUARD_DICT_ZIP) : $(apps_only_installed_files)
   $(call dist-for-goals,apps_only, $(PROGUARD_DICT_ZIP))
 
+  $(SYMBOLS_ZIP) : $(apps_only_installed_files)
+  $(call dist-for-goals,apps_only, $(SYMBOLS_ZIP))
+
 .PHONY: apps_only
 apps_only: $(unbundled_build_modules)
 
diff --git a/tools/releasetools/edify_generator.py b/tools/releasetools/edify_generator.py
index e4b9252..7d318a3 100644
--- a/tools/releasetools/edify_generator.py
+++ b/tools/releasetools/edify_generator.py
@@ -323,6 +323,10 @@
     """Append text verbatim to the output script."""
     self.script.append(extra)
 
+  def Unmount(self, mount_point):
+    self.script.append('unmount("%s");' % (mount_point,))
+    self.mounts.remove(mount_point);
+
   def UnmountAll(self):
     for p in sorted(self.mounts):
       self.script.append('unmount("%s");' % (p,))
diff --git a/tools/releasetools/ota_from_target_files b/tools/releasetools/ota_from_target_files
index 5cf9873..755e5c2 100755
--- a/tools/releasetools/ota_from_target_files
+++ b/tools/releasetools/ota_from_target_files
@@ -37,6 +37,10 @@
       Generate an incremental OTA using the given target-files zip as
       the starting build.
 
+  -v  (--verify)
+      Remount and verify the checksums of the files written to the
+      system and vendor (if used) partitions.  Incremental builds only.
+
   -o  (--oem_settings)  <file>
       Use the file to specify the expected OEM-specific properties
       on the OEM partition of the intended device.
@@ -104,6 +108,7 @@
 OPTIONS = common.OPTIONS
 OPTIONS.package_key = None
 OPTIONS.incremental_source = None
+OPTIONS.verify = False
 OPTIONS.require_verbatim = set()
 OPTIONS.prohibit_verbatim = set(("system/build.prop",))
 OPTIONS.patch_threshold = 0.95
@@ -939,7 +944,7 @@
           raise common.ExternalError("\"%s\" must be sent verbatim" % (fn,))
         print "send", fn, "verbatim"
         tf.AddToZip(output_zip)
-        verbatim_targets.append((fn, tf.size))
+        verbatim_targets.append((fn, tf.size, tf.sha1))
         if fn in target_data.keys():
           AddToKnownPaths(fn, known_paths)
       elif tf.sha1 != sf.sha1:
@@ -960,7 +965,7 @@
         # or a patch + rename cannot take place due to the target
         # directory not existing
         tf.AddToZip(output_zip)
-        verbatim_targets.append((tf.name, tf.size))
+        verbatim_targets.append((tf.name, tf.size, tf.sha1))
         if sf.name in renames:
           del renames[sf.name]
         AddToKnownPaths(tf.name, known_paths)
@@ -980,6 +985,13 @@
       so_far += sf.size
     return so_far
 
+  def EmitExplicitTargetVerification(self, script):
+    for fn, size, sha1 in self.verbatim_targets:
+      if (fn[-1] != "/"):
+        script.FileCheck("/"+fn, sha1)
+    for tf, _, _, _ in self.patch_list:
+      script.FileCheck(tf.name, tf.sha1)
+
   def RemoveUnneededFiles(self, script, extras=()):
     script.DeleteFiles(["/"+i[0] for i in self.verbatim_targets] +
                        ["/"+i for i in sorted(self.source_data)
@@ -1351,7 +1363,19 @@
 endif;
 """ % bcb_dev)
 
+  if OPTIONS.verify and system_diff:
+    script.Print("Remounting and verifying system partition files...")
+    script.Unmount("/system")
+    script.Mount("/system")
+    system_diff.EmitExplicitTargetVerification(script)
+
+  if OPTIONS.verify and vendor_diff:
+    script.Print("Remounting and verifying vendor partition files...")
+    script.Unmount("/vendor")
+    script.Mount("/vendor")
+    vendor_diff.EmitExplicitTargetVerification(script)
   script.AddToZip(target_zip, output_zip, input_path=OPTIONS.updater_binary)
+
   WriteMetadata(metadata, output_zip)
 
 
@@ -1387,6 +1411,8 @@
       OPTIONS.two_step = True
     elif o == "--no_signing":
       OPTIONS.no_signing = True
+    elif o in ("--verify"):
+      OPTIONS.verify = True
     elif o == "--block":
       OPTIONS.block_based = True
     elif o in ("-b", "--binary"):
@@ -1412,6 +1438,7 @@
                                               "block",
                                               "binary=",
                                               "oem_settings=",
+                                              "verify",
                                               "no_fallback_to_full",
                                               ],
                              extra_option_handler=option_handler)