diff --git a/scripts/code_size_compare.py b/scripts/code_size_compare.py
new file mode 100755
index 0000000..19a6c43
--- /dev/null
+++ b/scripts/code_size_compare.py
@@ -0,0 +1,210 @@
+#!/usr/bin/env python3
+
+"""
+Purpose
+
+This script is for comparing the size of the library files from two
+different Git revisions within an Mbed TLS repository.
+The results of the comparison is formatted as csv and stored at a
+configurable location.
+Note: must be run from Mbed TLS root.
+"""
+
+# Copyright The Mbed TLS Contributors
+# SPDX-License-Identifier: Apache-2.0
+#
+# 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.
+
+import argparse
+import os
+import subprocess
+import sys
+
+class CodeSizeComparison:
+    """compare code size between two Git revisions"""
+
+    def __init__(self, old_revision, new_revision, result_dir):
+        """
+        old_revision: revision to compare against
+        new_revision:
+        result_dir: directory for comparision result
+        """
+        self.repo_path = "."
+        self.result_dir = os.path.abspath(result_dir)
+        if os.path.exists(self.result_dir) is False:
+            os.makedirs(self.result_dir)
+
+        self.csv_dir = os.path.abspath("code_size_records/")
+        if os.path.exists(self.csv_dir) is False:
+            os.makedirs(self.csv_dir)
+
+        self.old_rev = old_revision
+        self.new_rev = new_revision
+        self.git_command = "git"
+        self.make_command = "make"
+
+    @staticmethod
+    def check_repo_path():
+        if not all(os.path.isdir(d) for d in ["include", "library", "tests"]):
+            raise Exception("Must be run from Mbed TLS root")
+
+    def _create_git_worktree(self, revision):
+        """Make a separate worktree for revision.
+        Do not modify the current worktree."""
+
+        if revision == "head":
+            print("Using current work directory.")
+            git_worktree_path = self.repo_path
+        else:
+            print("Creating git worktree for", revision)
+            git_worktree_path = os.path.join(self.repo_path, "temp-" + revision)
+            subprocess.check_output(
+                [self.git_command, "worktree", "add", "--detach",
+                 git_worktree_path, revision], cwd=self.repo_path,
+                stderr=subprocess.STDOUT
+            )
+        return git_worktree_path
+
+    def _build_libraries(self, git_worktree_path):
+        """Build libraries in the specified worktree."""
+
+        my_environment = os.environ.copy()
+        subprocess.check_output(
+            [self.make_command, "-j", "lib"], env=my_environment,
+            cwd=git_worktree_path, stderr=subprocess.STDOUT,
+        )
+
+    def _gen_code_size_csv(self, revision, git_worktree_path):
+        """Generate code size csv file."""
+
+        csv_fname = revision + ".csv"
+        print("Measuring code size for", revision)
+        result = subprocess.check_output(
+            ["size library/*.o"], cwd=git_worktree_path, shell=True
+        )
+        size_text = result.decode()
+        csv_file = open(os.path.join(self.csv_dir, csv_fname), "w")
+        for line in size_text.splitlines()[1:]:
+            data = line.split()
+            csv_file.write("{}, {}\n".format(data[5], data[3]))
+
+    def _remove_worktree(self, git_worktree_path):
+        """Remove temporary worktree."""
+        if git_worktree_path != self.repo_path:
+            print("Removing temporary worktree", git_worktree_path)
+            subprocess.check_output(
+                [self.git_command, "worktree", "remove", "--force",
+                 git_worktree_path], cwd=self.repo_path,
+                stderr=subprocess.STDOUT
+            )
+
+    def _get_code_size_for_rev(self, revision):
+        """Generate code size csv file for the specified git revision."""
+
+        # Check if the corresponding record exists
+        csv_fname = revision + ".csv"
+        if (revision != "head") and \
+           os.path.exists(os.path.join(self.csv_dir, csv_fname)):
+            print("Code size csv file for", revision, "already exists.")
+        else:
+            git_worktree_path = self._create_git_worktree(revision)
+            self._build_libraries(git_worktree_path)
+            self._gen_code_size_csv(revision, git_worktree_path)
+            self._remove_worktree(git_worktree_path)
+
+    def compare_code_size(self):
+        """Generate results of the size changes between two revisions,
+        old and new. Measured code size results of these two revisions
+        must be available"""
+
+        old_file = open(os.path.join(self.csv_dir, self.old_rev + ".csv"), "r")
+        new_file = open(os.path.join(self.csv_dir, self.new_rev + ".csv"), "r")
+        res_file = open(os.path.join(self.result_dir, "compare-" + self.old_rev
+                                     + "-" + self.new_rev + ".csv"), "w")
+        res_file.write("file_name, this_size, old_size, change, change %\n")
+        print("Generate comparision results.")
+
+        old_ds = {}
+        for line in old_file.readlines()[1:]:
+            cols = line.split(", ")
+            fname = cols[0]
+            size = int(cols[1])
+            if size != 0:
+                old_ds[fname] = size
+
+        new_ds = {}
+        for line in new_file.readlines()[1:]:
+            cols = line.split(", ")
+            fname = cols[0]
+            size = int(cols[1])
+            new_ds[fname] = size
+
+        for fname in new_ds:
+            this_size = new_ds[fname]
+            if fname in old_ds:
+                old_size = old_ds[fname]
+                change = this_size - old_size
+                change_pct = change / old_size
+                res_file.write("{}, {}, {}, {}, {:.2%}\n".format(fname, \
+                               this_size, old_size, change, float(change_pct)))
+            else:
+                res_file.write("{}, {}\n".format(fname, this_size))
+        return 1
+
+    def get_comparision_results(self):
+        """Compare size of library/*.o between self.old_rev and self.new_rev,
+        and generate the result file."""
+        self.check_repo_path()
+        self._get_code_size_for_rev(self.old_rev)
+        self._get_code_size_for_rev(self.new_rev)
+        return self.compare_code_size()
+
+def run_main():
+    parser = argparse.ArgumentParser(
+        description=(
+            """This script is for comparing the size of the library files
+            from two different Git revisions within an Mbed TLS repository.
+            The results of the comparison is formatted as csv, and stored at
+            a configurable location.
+            Note: must be run from Mbed TLS root."""
+        )
+    )
+    parser.add_argument(
+        "-r", "--result-dir", type=str, default="comparison",
+        help="directory where comparison result is stored, \
+              default is comparison",
+    )
+    parser.add_argument(
+        "-o", "--old-rev", type=str, help="old revision for comparison",
+        required=True,
+    )
+    parser.add_argument(
+        "-n", "--new-rev", type=str, default="head",
+        help="new revision for comparison, default is current work directory."
+    )
+    comp_args = parser.parse_args()
+
+    if os.path.isfile(comp_args.result_dir):
+        print("Error: {} is not a directory".format(comp_args.result_dir))
+        parser.exit()
+
+    old_revision = comp_args.old_rev
+    new_revision = comp_args.new_rev
+    result_dir = comp_args.result_dir
+    size_compare = CodeSizeComparison(old_revision, new_revision, result_dir)
+    return_code = size_compare.get_comparision_results()
+    sys.exit(return_code)
+
+
+if __name__ == "__main__":
+    run_main()