diff --git a/Android.mk b/Android.mk
index d333074..82a661a 100644
--- a/Android.mk
+++ b/Android.mk
@@ -111,6 +111,17 @@
 	$(call commit-change-for-toc,$(INTERNAL_PLATFORM_HIDDENAPI_DARK_GREYLIST))
 	$(call commit-change-for-toc,$(INTERNAL_PLATFORM_HIDDENAPI_BLACKLIST))
 
+$(INTERNAL_PLATFORM_HIDDENAPI_GREYLIST_METADATA): \
+    frameworks/base/tools/hiddenapi/merge_csv.py \
+    $(PRIVATE_METADATA_INPUTS)
+	frameworks/base/tools/hiddenapi/merge_csv.py $(PRIVATE_METADATA_INPUTS) > $@
+
+$(call dist-for-goals,droidcore,$(INTERNAL_PLATFORM_HIDDENAPI_WHITELIST))
+$(call dist-for-goals,droidcore,$(INTERNAL_PLATFORM_HIDDENAPI_LIGHT_GREYLIST))
+$(call dist-for-goals,droidcore,$(INTERNAL_PLATFORM_HIDDENAPI_DARK_GREYLIST))
+$(call dist-for-goals,droidcore,$(INTERNAL_PLATFORM_HIDDENAPI_BLACKLIST))
+$(call dist-for-goals,droidcore,$(INTERNAL_PLATFORM_HIDDENAPI_GREYLIST_METADATA))
+
 # Include subdirectory makefiles
 # ============================================================
 
diff --git a/tools/hiddenapi/merge_csv.py b/tools/hiddenapi/merge_csv.py
new file mode 100755
index 0000000..48c0755
--- /dev/null
+++ b/tools/hiddenapi/merge_csv.py
@@ -0,0 +1,40 @@
+#!/usr/bin/env python
+#
+# Copyright (C) 2018 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.
+"""
+Merge mutliple CSV files, possibly with different columns, writing to stdout.
+"""
+
+import csv
+import sys
+
+csv_readers = [
+    csv.DictReader(open(csv_file, 'rb'), delimiter=',', quotechar='|')
+    for csv_file in sys.argv[1:]
+]
+
+# Build union of all columns from source files:
+headers = set()
+for reader in csv_readers:
+  headers = headers.union(reader.fieldnames)
+
+# Concatenate all files to output:
+out = csv.DictWriter(sys.stdout, delimiter=',', quotechar='|', fieldnames = sorted(headers))
+out.writeheader()
+for reader in csv_readers:
+  for row in reader:
+    out.writerow(row)
+
+