diff --git a/.gitmodules b/.gitmodules
@@ -0,0 +1,4 @@
+[submodule "vendor/libgit2"]
+	path = vendor/libgit2
+[submodule "vendor/libgit2"]
+	url = https://github.com/nodegit/libgit2.git
diff --git a/generate/index.js b/generate/index.js
@@ -1,19 +1,34 @@
 var generateJson = require("./scripts/generateJson");
 var generateNativeCode = require("./scripts/generateNativeCode");
 var generateMissingTests = require("./scripts/generateMissingTests");
+var submoduleStatus = require("../lifecycleScripts/submodules/getStatus");
 
 module.exports = function generate() {
-  return new Promise(function(resolve, reject) {
-    try {
+  return submoduleStatus()
+    .then(function(statuses) {
+      var dirtySubmodules = statuses
+        .filter(function(status) {
+          return status.onNewCommit
+            || status.needsInitialization
+            || status.workDirDirty;
+        });
+
+      if (dirtySubmodules.length) {
+        console.log("WARNING - Some submodules are out-of-sync");
+        dirtySubmodules.forEach(function(submodule) {
+          console.log("\t" + submodule.name);
+        });
+      }
+    })
+    .then(function() {
       generateJson();
       generateNativeCode();
       generateMissingTests();
-      resolve();
-    }
-    catch(e) {
-      reject(e);
-    }
-  });
+    })
+    .catch(function(e) {
+      console.log("ERROR - Could not generate native code");
+      console.log(e);
+    });
 }
 
 if (require.main === module) {

diff --git a/generate/scripts/generateNativeCode.js b/generate/scripts/generateNativeCode.js
@@ -1,10 +1,7 @@
 const path = require("path");
 const promisify = require("promisify-node");
 const fse = promisify(require("fs-extra"));
-const exec = promisify(function(command, opts, callback) {
-  return require("child_process").exec(command, opts, callback);
-});
-
+const exec = require('../../utils/execPromise');
 const utils = require("./utils");
 
 module.exports = function generateNativeCode() {

diff --git a/lifecycleScripts/install.js b/lifecycleScripts/install.js
@@ -1,14 +1,11 @@
-var promisify = require("promisify-node");
 var path = require("path");
 var fs = require("fs");
 var cp = require("child_process");
 var prepareForBuild = require("./prepareForBuild");
-
-var exec = promisify(function(command, opts, callback) {
-  return cp.exec(command, opts, callback);
-});
+var exec = require("../utils/execPromise");
 
 var fromRegistry;
+
 try {
   fs.statSync(path.join(__dirname, "..", "include"));
   fs.statSync(path.join(__dirname, "..", "src"));
@@ -124,7 +121,6 @@ function build() {
     return arg;
   });
 
-  console.log(args);
   return new Promise(function(resolve, reject) {
     var child = cp.spawn(cmd, args, opts);
     child.on("close", function(code) {

diff --git a/lifecycleScripts/prepareForBuild.js b/lifecycleScripts/prepareForBuild.js
@@ -3,11 +3,11 @@ var path = require("path");
 
 var local = path.join.bind(path, __dirname);
 
+var submodules = require(local("submodules"));
 var configure = require(local("configureLibssh2"));
 var generate = require(local("../generate"));
 
 module.exports = function prepareForBuild() {
-
   return new Promise(function(resolve, reject) {
     cp.exec("npm install --ignore-scripts", function(err, stdout, stderr) {
       if (err) {
@@ -19,7 +19,11 @@ module.exports = function prepareForBuild() {
         console.info(stdout);
       }
     });
-  }).then(function() {
+  })
+  .then(function() {
+    return submodules();
+  })
+  .then(function() {
     return Promise.all([
       configure(),
       generate()

diff --git a/lifecycleScripts/submodules/getStatus.js b/lifecycleScripts/submodules/getStatus.js
@@ -0,0 +1,37 @@
+var path = require("path");
+var rootDir = path.join(__dirname, "../..");
+var exec = require(path.join(rootDir, "./utils/execPromise"));
+
+module.exports = function getStatus() {
+  return exec("git submodule status", { cwd: rootDir})
+    .then(function(stdout) {
+      function getStatusPromiseFromLine(line) {
+        var lineSections = line.trim().split(" ");
+        var onNewCommit = !!~lineSections[0].indexOf("+");
+        var needsInitialization = !!~lineSections[0].indexOf("-");
+        var commitOid = lineSections[0].replace("+", "").replace("-", "");
+        var name = lineSections[1];
+
+        return exec("git status", { cwd: path.join(rootDir, name)})
+          .then(function(workDirStatus) {
+            return {
+              commitOid: commitOid,
+              onNewCommit: onNewCommit,
+              name: name,
+              needsInitialization: needsInitialization,
+              workDirDirty: !~workDirStatus
+                .trim()
+                .split("\n")
+                .pop()
+                .indexOf("nothing to commit")
+            };
+          });
+      }
+
+      return Promise.all(stdout
+        .trim()
+        .split("\n")
+        .map(getStatusPromiseFromLine)
+      );
+    });
+};
diff --git a/lifecycleScripts/submodules/index.js b/lifecycleScripts/submodules/index.js
@@ -0,0 +1,74 @@
+var path = require("path");
+var rootDir = path.join(__dirname, "../..");
+
+var gitExecutableLocation = require(
+  path.join(rootDir, "./utils/gitExecutableLocation")
+);
+var submoduleStatus = require("./getStatus");
+
+var exec = require(path.join(rootDir, "./utils/execPromise"));
+
+module.exports = function submodules() {
+  return gitExecutableLocation()
+    .catch(function() {
+      console.log("ERROR - Compilation of NodeGit requires git CLI to be " +
+        "installed and on the path");
+
+      throw new Error("git CLI is not installed or not on the path");
+    })
+    .then(function() {
+      return submoduleStatus();
+    })
+    .then(function(statuses) {
+      function printSubmodule(submoduleName) {
+        console.log("\t" + submoduleName);
+      }
+
+      var dirtySubmodules = statuses
+      .filter(function(status) {
+        return status.workDirDirty && !status.needsInitialization;
+      })
+      .map(function(dirtySubmodule) {
+        return dirtySubmodule.name;
+      });
+
+      if (dirtySubmodules.length) {
+        console.log(
+          "ERROR - The following submodules have uncommited changes:"
+        );
+        dirtySubmodules.forEach(printSubmodule);
+        console.log(
+          "\nThey must either be committed or discarded before we build"
+        );
+
+        throw new Error("Dirty Submodules: " + dirtySubmodules.join(" "));
+      }
+
+      var outOfSyncSubmodules = statuses
+        .filter(function(status) {
+          return status.onNewCommit && !status.needsInitialization;
+        })
+        .map(function(outOfSyncSubmodule) {
+          return outOfSyncSubmodule.name;
+        });
+
+      if (outOfSyncSubmodules.length) {
+        console.log(
+          "WARNING - The following submodules are pointing to an new commit:"
+        );
+        outOfSyncSubmodules.forEach(printSubmodule);
+        console.log("\nThey will not be updated.");
+      }
+
+      return Promise.all(statuses
+        .filter(function(status) {
+          return !status.onNewCommit;
+        })
+        .map(function(submoduleToUpdate) {
+          return exec(
+            "git submodule update --init --recursive " + submoduleToUpdate.name
+          );
+        })
+      );
+    });
+};
diff --git a/test/runner.js b/test/runner.js
@@ -2,6 +2,7 @@ var promisify = require("promisify-node");
 var fse = promisify("fs-extra");
 var path = require("path");
 var local = path.join.bind(path, __dirname);
+var exec = require('../utils/execPromise');
 
 var NodeGit = require('..');
 
@@ -13,11 +14,6 @@ if(process.env.NODEGIT_TEST_THREADSAFETY) {
   NodeGit.setThreadSafetyStatus(NodeGit.THREAD_SAFETY.ENABLED_FOR_ASYNC_ONLY);
 }
 
-// Have to wrap exec, since it has a weird callback signature.
-var exec = promisify(function(command, opts, callback) {
-  return require("child_process").exec(command, opts, callback);
-});
-
 var workdirPath = local("repos/workdir");
 
 before(function() {

diff --git a/test/tests/commit.js b/test/tests/commit.js
@@ -8,10 +8,7 @@ var leakTest = require("../utils/leak_test");
 
 var local = path.join.bind(path, __dirname);
 
-// Have to wrap exec, since it has a weird callback signature.
-var exec = promisify(function(command, opts, callback) {
-  return require("child_process").exec(command, opts, callback);
-});
+var exec = require("../../utils/execPromise");
 
 describe("Commit", function() {
   var NodeGit = require("../../");

diff --git a/test/tests/config.js b/test/tests/config.js
@@ -1,12 +1,8 @@
 var assert = require("assert");
 var path = require("path");
 var local = path.join.bind(path, __dirname);
-var promisify = require("promisify-node");
 
-// Have to wrap exec, since it has a weird callback signature.
-var exec = promisify(function(command, opts, callback) {
-  return require("child_process").exec(command, opts, callback);
-});
+var exec = require("../../utils/execPromise");
 
 describe("Config", function() {
   var NodeGit = require("../../");

diff --git a/test/tests/refs.js b/test/tests/refs.js
@@ -1,12 +1,8 @@
 var assert = require("assert");
 var path = require("path");
-var promisify = require("promisify-node");
 var local = path.join.bind(path, __dirname);
 
-// Have to wrap exec, since it has a weird callback signature.
-var exec = promisify(function(command, opts, callback) {
-  return require("child_process").exec(command, opts, callback);
-});
+var exec = require("../../utils/execPromise");
 
 describe("Reference", function() {
   var NodeGit = require("../../");

diff --git a/test/tests/signature.js b/test/tests/signature.js
@@ -1,12 +1,8 @@
 var assert = require("assert");
 var path = require("path");
 var local = path.join.bind(path, __dirname);
-var promisify = require("promisify-node");
 
-// Have to wrap exec, since it has a weird callback signature.
-var exec = promisify(function(command, opts, callback) {
-  return require("child_process").exec(command, opts, callback);
-});
+var exec = require("../../utils/execPromise");
 
 describe("Signature", function() {
   var NodeGit = require("../../");

diff --git a/test/tests/stage.js b/test/tests/stage.js
@@ -3,9 +3,7 @@ var path = require("path");
 var promisify = require("promisify-node");
 var fse = promisify(require("fs-extra"));
 
-var exec = promisify(function(command, opts, callback) {
-  return require("child_process").exec(command, opts, callback);
-});
+var exec = require("../../utils/execPromise");
 
 describe("Stage", function() {
   var RepoUtils = require("../utils/repository_setup");

diff --git a/test/tests/status.js b/test/tests/status.js
@@ -3,9 +3,7 @@ var path = require("path");
 var promisify = require("promisify-node");
 var fse = promisify(require("fs-extra"));
 var local = path.join.bind(path, __dirname);
-var exec = promisify(function(command, opts, callback) {
-  return require("child_process").exec(command, opts, callback);
-});
+var exec = require("../../utils/execPromise");
 
 describe("Status", function() {
   var NodeGit = require("../../");

diff --git a/test/tests/status_list.js b/test/tests/status_list.js
@@ -3,9 +3,7 @@ var path = require("path");
 var promisify = require("promisify-node");
 var fse = promisify(require("fs-extra"));
 var local = path.join.bind(path, __dirname);
-var exec = promisify(function(command, opts, callback) {
-  return require("child_process").exec(command, opts, callback);
-});
+var exec = require("../../utils/execPromise");
 
 describe("StatusList", function() {
   var NodeGit = require("../../");

diff --git a/utils/execPromise.js b/utils/execPromise.js
@@ -0,0 +1,6 @@
+var promisify = require("promisify-node");
+var cp = require('child_process');
+
+module.exports = promisify(function(command, opts, callback) {
+  return cp.exec(command, opts, callback);
+});
diff --git a/utils/gitExecutableLocation.js b/utils/gitExecutableLocation.js
@@ -0,0 +1,23 @@
+var cp = require("child_process");
+
+module.exports = function gitExecutableLocation() {
+  return new Promise(function(resolve, reject) {
+    var cmd;
+
+    if (process.platform === "win32") {
+      cmd = "where git";
+    }
+    else {
+      cmd = "which git";
+    }
+
+    cp.exec(cmd, function(err, stdout, stderr) {
+      if (err) {
+        reject(err, stderr);
+      }
+      else {
+        resolve(stdout);
+      }
+    });
+  });
+};
diff --git a/vendor/libgit2 b/vendor/libgit2
diff --git a/vendor/libgit2/.HEADER b/vendor/libgit2/.HEADER