diff --git a/upstream_utils/update_json.py b/upstream_utils/update_json.py
new file mode 100755
index 0000000..1f5839c
--- /dev/null
+++ b/upstream_utils/update_json.py
@@ -0,0 +1,78 @@
+#!/usr/bin/env python3
+
+import os
+import shutil
+
+from upstream_utils import (
+    get_repo_root,
+    clone_repo,
+    walk_if,
+    git_am,
+)
+
+
+def main():
+    upstream_root = clone_repo("https://github.com/nlohmann/json", "v3.11.2")
+    wpilib_root = get_repo_root()
+    wpiutil = os.path.join(wpilib_root, "wpiutil")
+
+    # Apply patches to upstream Git repo
+    os.chdir(upstream_root)
+    for f in [
+        "0001-Remove-version-from-namespace.patch",
+        "0002-Make-serializer-public.patch",
+        "0003-Make-dump_escaped-take-std-string_view.patch",
+        "0004-Add-llvm-stream-support.patch",
+    ]:
+        git_am(
+            os.path.join(wpilib_root, "upstream_utils/json_patches", f),
+            use_threeway=True,
+        )
+
+    # Delete old install
+    for d in [
+        "src/main/native/thirdparty/json/include",
+    ]:
+        shutil.rmtree(os.path.join(wpiutil, d), ignore_errors=True)
+
+    # Create lists of source and destination files
+    os.chdir(os.path.join(upstream_root, "include/nlohmann"))
+    files = walk_if(".", lambda dp, f: True)
+    src_include_files = [
+        os.path.join(os.path.join(upstream_root, "include/nlohmann"), f) for f in files
+    ]
+    wpiutil_json_root = os.path.join(
+        wpiutil, "src/main/native/thirdparty/json/include/wpi"
+    )
+    dest_include_files = [
+        os.path.join(wpiutil_json_root, f.replace(".hpp", ".h")) for f in files
+    ]
+
+    # Copy json header files into allwpilib
+    for i in range(len(src_include_files)):
+        dest_dir = os.path.dirname(dest_include_files[i])
+        if not os.path.exists(dest_dir):
+            os.makedirs(dest_dir)
+        shutil.copyfile(src_include_files[i], dest_include_files[i])
+
+    for include_file in dest_include_files:
+        with open(include_file) as f:
+            content = f.read()
+
+        # Rename namespace from nlohmann to wpi
+        content = content.replace("namespace nlohmann", "namespace wpi")
+        content = content.replace("nlohmann::", "wpi::")
+
+        # Fix internal includes
+        content = content.replace(".hpp>", ".h>")
+        content = content.replace("include <nlohmann/", "include <wpi/")
+
+        # Fix include guards and other #defines
+        content = content.replace("NLOHMANN_", "WPI_")
+
+        with open(include_file, "w") as f:
+            f.write(content)
+
+
+if __name__ == "__main__":
+    main()