diff --git a/pkgs/by-name/gc/gclient2nix/gclient-unpack-hook.sh b/pkgs/by-name/gc/gclient2nix/gclient-unpack-hook.sh
new file mode 100644
index 000000000000..6dac91b9e25a
--- /dev/null
+++ b/pkgs/by-name/gc/gclient2nix/gclient-unpack-hook.sh
@@ -0,0 +1,28 @@
+# shellcheck shell=bash
+
+gclientUnpackHook() {
+    echo "Executing gclientUnpackHook"
+
+    runHook preUnpack
+
+    if [ -z "${gclientDeps-}" ]; then
+        echo "gclientDeps missing"
+        exit 1
+    fi
+
+    for dep in $(@jq@ -c "to_entries[]" "$gclientDeps")
+    do
+        local name="$(echo "$dep" | @jq@ -r .key)"
+        echo "copying $name..."
+        local path="$(echo "$dep" | @jq@ -r .value.path)"
+        mkdir -p $(dirname "$name")
+        cp -r "$path/." "$name"
+        chmod u+w -R "$name"
+    done
+
+    runHook postUnpack
+}
+
+if [ -z "${dontGclientUnpack-}" ] && [ -z "${unpackPhase-}" ]; then
+  unpackPhase=(gclientUnpackHook)
+fi
diff --git a/pkgs/by-name/gc/gclient2nix/package.nix b/pkgs/by-name/gc/gclient2nix/package.nix
index 17662ab5d714..ee7251b9ffa7 100644
--- a/pkgs/by-name/gc/gclient2nix/package.nix
+++ b/pkgs/by-name/gc/gclient2nix/package.nix
@@ -6,9 +6,49 @@
   path,
   fetchgit,
   nurl,
+  writers,
+  callPackage,
+  fetchFromGitiles,
+  fetchFromGitHub,
 }:
 
 let
+  fetchers = {
+    inherit fetchgit fetchFromGitiles fetchFromGitHub;
+  };
+
+  importGclientDeps =
+    depsAttrsOrFile:
+    let
+      depsAttrs = if lib.isAttrs depsAttrsOrFile then depsAttrsOrFile else lib.importJSON depsAttrsOrFile;
+      fetchdep = dep: fetchers.${dep.fetcher} dep.args;
+      fetchedDeps = lib.mapAttrs (_name: fetchdep) depsAttrs;
+      manifestContents = lib.mapAttrs (_: dep: {
+        path = dep;
+      }) fetchedDeps;
+      manifest = writers.writeJSON "gclient-manifest.json" manifestContents;
+    in
+    manifestContents
+    // {
+      inherit manifest;
+      __toString = _: manifest;
+    };
+
+  gclientUnpackHook = callPackage (
+    {
+      lib,
+      makeSetupHook,
+      jq,
+    }:
+
+    makeSetupHook {
+      name = "gclient-unpack-hook";
+      substitutions = {
+        jq = lib.getExe jq;
+      };
+    } ./gclient-unpack-hook.sh
+  ) { };
+
   python = python3.withPackages (
     ps: with ps; [
       joblib
@@ -32,6 +72,10 @@ runCommand "gclient2nix"
       rev = "452fe3be37f78fbecefa1b4b0d359531bcd70d0d";
       hash = "sha256-8IiJOm0FLa/u1Vd96tb33Ruj4IUTCeYgBpTk88znhPw=";
     };
+
+    passthru = {
+      inherit fetchers importGclientDeps gclientUnpackHook;
+    };
   }
   ''
     mkdir -p $out/bin