diff --git a/lib/vagrant/action/builtin.rb b/lib/vagrant/action/builtin.rb
index fe0e38c43..962f5662c 100644
--- a/lib/vagrant/action/builtin.rb
+++ b/lib/vagrant/action/builtin.rb
@@ -9,6 +9,7 @@ module Vagrant
         use VM::Import
         use VM::Customize
         use VM::ForwardPorts
+        use VM::ShareFolders
       end
 
       register :up, up
diff --git a/lib/vagrant/action/vm/share_folders.rb b/lib/vagrant/action/vm/share_folders.rb
new file mode 100644
index 000000000..905402f58
--- /dev/null
+++ b/lib/vagrant/action/vm/share_folders.rb
@@ -0,0 +1,105 @@
+module Vagrant
+  class Action
+    module VM
+      class ShareFolders
+        def initialize(app, env)
+          @app = app
+          @env = env
+        end
+
+        def call(env)
+          @env = env
+
+          clear_shared_folders
+          create_metadata
+
+          @app.call(env)
+
+          mount_shared_folders
+          setup_unison
+        end
+
+        # This method returns an actual list of VirtualBox shared
+        # folders to create and their proper path.
+        def shared_folders
+          @env.env.config.vm.shared_folders.inject({}) do |acc, data|
+            key, value = data
+
+            # This to prevent overwriting the actual shared folders data
+            value = value.dup
+
+            if value[:sync]
+              # Syncing this folder. Change the guestpath to reflect
+              # what we're actually mounting.
+              value[:original] = value.dup
+              value[:guestpath] = "#{value[:guestpath]}#{@env.env.config.unison.folder_suffix}"
+            end
+
+            acc[key] = value
+            acc
+          end
+        end
+
+        # This method returns the list of shared folders which are to
+        # be synced via unison.
+        def unison_folders
+          shared_folders.inject({}) do |acc, data|
+            key, value = data
+            acc[key] = value if !!value[:sync]
+            acc
+          end
+        end
+
+        def clear_shared_folders
+          if @env["vm"].vm.shared_folders.length > 0
+            @env.logger.info "Clearing previously set shared folders..."
+
+            folders = @env["vm"].vm.shared_folders.dup
+            folders.each do |shared_folder|
+              shared_folder.destroy
+            end
+
+            @env["vm"].reload!
+          end
+        end
+
+        def create_metadata
+          @env.logger.info "Creating shared folders metadata..."
+
+          shared_folders.each do |name, data|
+            folder = VirtualBox::SharedFolder.new
+            folder.name = name
+            folder.host_path = File.expand_path(data[:hostpath], @env.env.root_path)
+            @env["vm"].vm.shared_folders << folder
+          end
+
+          @env["vm"].vm.save
+        end
+
+        def mount_shared_folders
+          @env.logger.info "Mounting shared folders..."
+
+          @env["vm"].ssh.execute do |ssh|
+            shared_folders.each do |name, data|
+              @env.logger.info "-- #{name}: #{data[:guestpath]}"
+              @env["vm"].system.mount_shared_folder(ssh, name, data[:guestpath])
+            end
+          end
+        end
+
+        def setup_unison
+          return if unison_folders.empty?
+
+          @env["vm"].ssh.execute do |ssh|
+            @env["vm"].system.prepare_unison(ssh)
+
+            @env.logger.info "Creating unison crontab entries..."
+            unison_folders.each do |name, data|
+              @env["vm"].system.create_unison(ssh, data)
+            end
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/test/vagrant/action/vm/share_folders_test.rb b/test/vagrant/action/vm/share_folders_test.rb
new file mode 100644
index 000000000..f5ba746bc
--- /dev/null
+++ b/test/vagrant/action/vm/share_folders_test.rb
@@ -0,0 +1,217 @@
+require File.join(File.dirname(__FILE__), '..', '..', '..', 'test_helper')
+
+class ShareFoldersVMActionTest < Test::Unit::TestCase
+  setup do
+    @klass = Vagrant::Action::VM::ShareFolders
+    @app, @env = mock_action_data
+
+    @vm = mock("vm")
+    @vm.stubs(:name).returns("foo")
+    @vm.stubs(:ssh).returns(mock("ssh"))
+    @vm.stubs(:system).returns(mock("system"))
+    @env["vm"] = @vm
+
+    @internal_vm = mock("internal")
+    @vm.stubs(:vm).returns(@internal_vm)
+
+    @instance = @klass.new(@app, @env)
+  end
+
+  def stub_shared_folders
+    env = mock_environment do |config|
+      config.vm.shared_folders.clear
+
+      if block_given?
+        yield config
+      else
+        folders = [%w{foo fooguest foohost}, %w{bar barguest barhost}]
+        folders.each do |data|
+          config.vm.share_folder(*data)
+        end
+      end
+    end
+
+    @env.stubs(:env).returns(env)
+    env.config.vm.shared_folders
+  end
+
+  context "calling" do
+    should "run the methods in the proper order" do
+      before_seq = sequence("before")
+      @instance.expects(:clear_shared_folders).once.in_sequence(before_seq)
+      @instance.expects(:create_metadata).once.in_sequence(before_seq)
+      @app.expects(:call).with(@env).in_sequence(before_seq)
+      @instance.expects(:mount_shared_folders).once.in_sequence(before_seq)
+      @instance.expects(:setup_unison).once.in_sequence(before_seq)
+
+      @instance.call(@env)
+    end
+  end
+
+  context "collecting shared folders" do
+    setup do
+      File.stubs(:expand_path).returns("baz")
+    end
+
+    should "return a hash of the shared folders" do
+      data = {
+        "foo" => %W[bar baz],
+        "bar" => %W[foo baz]
+      }
+
+      stub_shared_folders do |config|
+        data.each do |name, value|
+          config.vm.share_folder(name, *value)
+        end
+      end
+
+      result = @instance.shared_folders
+      assert_equal data.length, result.length
+      data.each do |name, value|
+        guest, host = value
+        assert_equal guest, result[name][:guestpath]
+        assert_equal host, result[name][:hostpath]
+      end
+    end
+
+    should "append sync suffix if sync enabled to a folder" do
+      name = "foo"
+      guest = "bar"
+      host = "baz"
+
+      stub_shared_folders do |config|
+        config.vm.share_folder(name, guest, host, :sync => true)
+      end
+
+      result = @instance.shared_folders
+      assert_equal "#{guest}#{@env.env.config.unison.folder_suffix}", result[name][:guestpath]
+      assert_equal guest, result[name][:original][:guestpath]
+    end
+
+    should "not destroy original hash" do
+      @folders = stub_shared_folders do |config|
+        config.vm.share_folder("foo", "bar", "baz", :sync => true)
+      end
+
+      folder = @folders["foo"].dup
+
+      @instance.shared_folders
+      assert_equal folder, @env.env.config.vm.shared_folders["foo"]
+    end
+  end
+
+  context "unison shared folders" do
+    setup do
+      @folders = stub_shared_folders do |config|
+        config.vm.share_folder("foo", "bar", "baz", :sync => true)
+        config.vm.share_folder("bar", "foo", "baz")
+      end
+    end
+
+    should "only return the folders marked for syncing" do
+      result = @instance.unison_folders
+      assert_equal 1, result.length
+      assert result.has_key?("foo")
+      assert !result.has_key?("bar")
+    end
+  end
+
+  context "clearing shared folders" do
+    setup do
+      @shared_folder = mock("shared_folder")
+      @shared_folders = [@shared_folder]
+      @internal_vm.stubs(:shared_folders).returns(@shared_folders)
+    end
+
+    should "call destroy on each shared folder then reload" do
+      destroy_seq = sequence("destroy")
+      @shared_folders.each do |sf|
+        sf.expects(:destroy).once.in_sequence(destroy_seq)
+      end
+
+      @vm.expects(:reload!).once.in_sequence(destroy_seq)
+      @instance.clear_shared_folders
+    end
+
+    should "do nothing if no shared folders existed" do
+      @shared_folders.clear
+      @vm.expects(:reload!).never
+      @instance.clear_shared_folders
+    end
+  end
+
+  context "setting up shared folder metadata" do
+    setup do
+      stub_shared_folders
+    end
+
+    should "add all shared folders to the VM" do
+      shared_folders = []
+      data = %W[foo bar]
+      shared_folders.expects(:<<).times(data.length).with() do |sf|
+        hostpath = File.expand_path("#{sf.name}host", @env.env.root_path)
+        assert data.include?(sf.name)
+        assert_equal hostpath, sf.host_path
+        true
+      end
+
+      @internal_vm.stubs(:shared_folders).returns(shared_folders)
+      @internal_vm.expects(:save).once
+
+      @instance.create_metadata
+    end
+  end
+
+  context "mounting the shared folders" do
+    setup do
+      @folders = stub_shared_folders
+      @ssh = mock("ssh")
+      @vm.ssh.stubs(:execute).yields(@ssh)
+      @vm.system.stubs(:mount_shared_folder)
+    end
+
+    should "mount all shared folders to the VM" do
+      mount_seq = sequence("mount_seq")
+      @folders.each do |name, data|
+        @vm.system.expects(:mount_shared_folder).with(@ssh, name, data[:guestpath]).in_sequence(mount_seq)
+      end
+
+      @instance.mount_shared_folders
+    end
+  end
+
+  context "setting up unison" do
+    setup do
+      @ssh = mock("ssh")
+      @vm.ssh.stubs(:execute).yields(@ssh)
+
+      @folders = stub_shared_folders do |config|
+        config.vm.share_folder("foo", "bar", "baz", :sync => true)
+        config.vm.share_folder("bar", "foo", "baz")
+      end
+    end
+
+    should "do nothing if unison folders is empty" do
+      @instance.stubs(:unison_folders).returns({})
+      @vm.ssh.expects(:execute).never
+      @instance.setup_unison
+    end
+
+    should "prepare unison then create for each folder" do
+      seq = sequence("unison seq")
+      @vm.system.expects(:prepare_unison).with(@ssh).once.in_sequence(seq)
+      @instance.unison_folders.each do |name, data|
+        if data[:sync]
+          @vm.system.expects(:create_unison).with do |ssh, opts|
+            assert_equal @ssh, ssh
+            assert_equal data, opts
+
+            true
+          end
+        end
+      end
+
+      @instance.setup_unison
+    end
+  end
+end