diff --git a/lib/warbler/traits/compiled_gems.rb b/lib/warbler/traits/compiled_gems.rb
new file mode 100644
index 00000000..884398c5
--- /dev/null
+++ b/lib/warbler/traits/compiled_gems.rb
@@ -0,0 +1,96 @@
+# encoding: UTF-8
+
+module Warbler
+  module Traits
+    class CompiledGems
+
+      include Trait
+      include RakeHelper
+
+      def self.detect?
+        # Don't have access to @config here, so always return true and check
+        # @config.compile_gems later.
+        true
+      end
+
+      def self.requirements
+        [Traits::Jar, Traits::War]
+      end
+
+      def after_configure
+        if @config.compile_gems
+          define_tasks
+        end
+      end
+
+      def update_archive(jar)
+        if @config.compile_gems
+          copy_excluded_files(jar)
+          fix_double_web_inf_paths(jar)
+        end
+      end
+
+      private
+
+      # When building .war files, warbler mistakenly adds WEB-INF/ twice to
+      # the beginning of each individual .class file, which causes them to not
+      # get copied over into the package.
+      def fix_double_web_inf_paths(jar)
+        new_files = jar.files.each_with_object({}) do |(inside_jar, file_system_location), ret|
+          new_inside_jar = inside_jar.gsub(/\AWEB-INF\/WEB-INF/, 'WEB-INF')
+          ret[new_inside_jar] = file_system_location
+        end
+
+        jar.instance_variable_set(:'@files', new_files)
+      end
+
+      # Hack to copy over files excluded from compilation.
+      #
+      # Warbler doesn't provide a way to exclude files only from compilation,
+      # then copy those files over to the jar/war. This method executes before
+      # files get copied and updates the jar's file map.
+      def copy_excluded_files(jar)
+        @config.gems.specs(@config.gem_dependencies).each do |spec|
+          full_gem_path = Pathname.new(spec.full_gem_path)
+          FileList["#{full_gem_path.to_s}/**/*"].each do |src|
+            f = Pathname.new(src).relative_path_from(full_gem_path).to_s
+            if @config.gem_excludes.any? { |rx| f =~ rx }
+              jar.files[jar.apply_pathmaps(@config, File.join(spec.full_name, f), :gems)] = src
+            end
+          end
+        end
+      end
+
+      # Hack to compile gems that come from git repositories.
+      #
+      # For some reason, warbler keeps git-based gems in a different hash,
+      # separate from all the other gems. This means they miss out on
+      # getting compiled, among other things.
+      def fix_gems
+        @config.bundler[:git_specs].each do |git_spec|
+          @config.gems << git_spec
+        end
+
+        @config.bundler.delete(:git_specs)
+      end
+
+      def define_tasks
+        namespace :jar do
+          task :before_compiled do
+            fix_gems
+          end
+        end
+
+        namespace :war do
+          task :before_compiled do
+            fix_gems
+          end
+        end
+
+        task 'jar:compiled' => 'jar:before_compiled'
+        task 'war:compiled' => 'war:before_compiled'
+      end
+
+    end
+  end
+end