diff --git a/open_pdks/gds_change_date.py b/open_pdks/gds_change_date.py
new file mode 100755
index 0000000..4032736
--- /dev/null
+++ b/open_pdks/gds_change_date.py
@@ -0,0 +1,160 @@
+#!/usr/bin/env python3
+# Copyright 2021 SkyWater PDK Authors
+#
+# 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.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+"""
+Script to read a GDS file, modify the timestamp(s), and rewrite the GDS file.
+"""
+
+import os
+import sys
+import datetime
+
+def usage():
+    print('change_gds_date.py <create_stamp> <mod_stamp> <path_to_gds_in> [<path_to_gds_out>]')
+
+if __name__ == '__main__':
+    debug = False
+
+    if len(sys.argv) == 1:
+        print("No options given to change_gds_date.py.")
+        usage()
+        sys.exit(0)
+
+    optionlist = []
+    arguments = []
+
+    for option in sys.argv[1:]:
+        if option.find('-', 0) == 0:
+            optionlist.append(option)
+        else:
+            arguments.append(option)
+
+    if len(arguments) < 3 or len(arguments) > 4:
+        print("Wrong number of arguments given to change_gds_date.py.")
+        usage()
+        sys.exit(0)
+
+    if '-debug' in optionlist:
+        debug = True
+
+    createstamp = arguments[0]
+    modstamp = arguments[1]
+    source = arguments[2]
+
+    # If modstamp is zero or negative, then set the modification timestamp
+    # to be the same as the creation timestamp.
+    try:
+        if int(modstamp) <= 0:
+            modstamp = createstamp
+    except:
+        pass
+
+    # If only three arguments are provided, then overwrite the source file.
+    if len(arguments) == 4:
+        dest = arguments[3]
+    else:
+        dest = arguments[2]
+
+    sourcedir = os.path.split(source)[0]
+    gdsinfile = os.path.split(source)[1]
+
+    destdir = os.path.split(dest)[0]
+    gdsoutfile = os.path.split(dest)[1]
+
+    with open(source, 'rb') as ifile:
+        gdsdata = ifile.read()
+
+    # Generate 12-byte modification timestamp data from date.
+    try:
+        modtime = datetime.datetime.utcfromtimestamp(int(modstamp))
+    except:
+        modtime = datetime.datetime.strptime(modstamp, "%m/%d/%Y %H:%M:%S")
+
+    modyear = modtime.year - 1900
+
+    year = modyear.to_bytes(2, byteorder='big')
+    month = modtime.month.to_bytes(2, byteorder='big')
+    day = modtime.day.to_bytes(2, byteorder='big')
+    hour = modtime.hour.to_bytes(2, byteorder='big')
+    minute = modtime.minute.to_bytes(2, byteorder='big')
+    second = modtime.second.to_bytes(2, byteorder='big')
+
+    gdsmodstamp = year + month + day + hour + minute + second
+
+    # Generate 12-byte creation timestamp data from date.
+    try:
+        createtime = datetime.datetime.utcfromtimestamp(int(createstamp))
+    except:
+        createtime = datetime.datetime.strptime(createstamp, "%m/%d/%Y %H:%M:%S")
+
+    createyear = createtime.year - 1900
+
+    year = createyear.to_bytes(2, byteorder='big')
+    month = createtime.month.to_bytes(2, byteorder='big')
+    day = createtime.day.to_bytes(2, byteorder='big')
+    hour = createtime.hour.to_bytes(2, byteorder='big')
+    minute = createtime.minute.to_bytes(2, byteorder='big')
+    second = createtime.second.to_bytes(2, byteorder='big')
+
+    gdscreatestamp = year + month + day + hour + minute + second
+
+    # To be done:  Allow the user to select which datestamps to change
+    # (library or structure).  Otherwise, apply the same datestamps to both.
+
+    recordtypes = ['beginstr', 'beginlib']
+    recordfilter = [5, 1]
+
+    datalen = len(gdsdata)
+    dataptr = 0
+    while dataptr < datalen:
+        # Read stream records up to any string, then search for search text.
+        bheader = gdsdata[dataptr:dataptr + 2]
+        reclen = int.from_bytes(bheader, 'big')
+        if reclen == 0:
+            print('Error: found zero-length record at position ' + str(dataptr))
+            break
+
+        rectype = gdsdata[dataptr + 2]
+        datatype = gdsdata[dataptr + 3]
+
+        brectype = rectype.to_bytes(1, byteorder='big')
+        bdatatype = datatype.to_bytes(1, byteorder='big')
+
+        if rectype in recordfilter:
+            # Datatype should be 2
+            if datatype != 2:
+                print('Error:  Header data type is not 2-byte integer!')
+            if reclen != 28:
+                print('Error:  Header record length is not 28!')
+            if debug:
+                print('Record type = ' + str(rectype) + ' data type = ' + str(datatype) + ' length = ' + str(reclen))
+
+            before = gdsdata[0:dataptr]
+            after = gdsdata[dataptr + reclen:]
+
+            # Assemble the new record
+            newrecord = bheader + brectype + bdatatype + gdscreatestamp + gdsmodstamp
+            # Reassemble the GDS data around the new record
+            gdsdata = before + newrecord + after
+
+        # Advance the pointer past the data
+        dataptr += reclen
+
+    with open(dest, 'wb') as ofile:
+        ofile.write(gdsdata)
+
+    exit(0)
diff --git a/open_pdks/post-open_pdks.sh b/open_pdks/post-open_pdks.sh
new file mode 100755
index 0000000..0273fc6
--- /dev/null
+++ b/open_pdks/post-open_pdks.sh
@@ -0,0 +1,28 @@
+#!/usr/bin/env bash
+# Copyright 2021 SkyWater PDK Authors
+#
+# 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.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+set -xe
+set -o pipefail
+
+export PATH=/host/out/magic/bin:$PATH
+
+# Clear timestamps in magic files
+find out/pdk-* -name '*.mag' -exec sed -i -e's/timestamp [0-9]\+/timestamp 0/' \{\} \+
+
+# Clear timestamps in GDS files
+find out/pdk-* -name '*.gds' -exec /host/git/builder/open_pdks/gds_change_date.py 1 0 \{\}
+#find out/pdk-* -name '*.gds' -print | parallel -v /host/git/builder/open_pdks/gds_change_date.py 1 0 \{\}
diff --git a/open_pdks/run.sh b/open_pdks/run.sh
index 51bf4f7..c87401f 100755
--- a/open_pdks/run.sh
+++ b/open_pdks/run.sh
@@ -95,6 +95,7 @@
 
 # Run `./configure` targeting the output directory.
 $DOCKER_CMD bash /host/$SCRIPT_DIR_REL/build-open_pdks.sh
+$DOCKER_CMD bash /host/$SCRIPT_DIR_REL/post-open_pdks.sh
 
 # Tar up result.
 find out/pdk-* | sort | tee pdk.files