diff --git a/Gemfile b/Gemfile
index e9b751e79..9f45d1679 100644
--- a/Gemfile
+++ b/Gemfile
@@ -17,6 +17,7 @@ gem "nokogiri", "~> 1.10.0"
 gem 'i18n', '~> 1.8.2'
 gem "rbpdf", "~> 1.20.0"
 gem 'addressable'
+gem 'rubyzip', '~> 2.2.0'
 
 # Windows does not include zoneinfo files, so bundle the tzinfo-data gem
 gem 'tzinfo-data', platforms: [:mingw, :x64_mingw, :mswin]
diff --git a/app/controllers/attachments_controller.rb b/app/controllers/attachments_controller.rb
index 4a880793e..dbebd5a34 100644
--- a/app/controllers/attachments_controller.rb
+++ b/app/controllers/attachments_controller.rb
@@ -19,6 +19,8 @@
 
 class AttachmentsController < ApplicationController
   before_action :find_attachment, :only => [:show, :download, :thumbnail, :update, :destroy]
+  before_action :find_container, :only => [:edit_all, :update_all, :download_all]
+  before_action :find_downloadable_attachments, :only => :download_all
   before_action :find_editable_attachments, :only => [:edit_all, :update_all]
   before_action :file_readable, :read_authorize, :only => [:show, :download, :thumbnail]
   before_action :update_authorize, :only => :update
@@ -132,6 +134,18 @@ class AttachmentsController < ApplicationController
     render :action => 'edit_all'
   end
 
+  def download_all
+    Tempfile.create('attachments_zip', Rails.root.join('tmp')) do |tempfile|
+      zip_file = Attachment.attachments_to_zip(tempfile, @attachments)
+      if zip_file.nil?
+        render_404
+        return
+      end
+      send_data(File.read(zip_file.path), :type => 'application/zip',
+                :filename => "#{@container.class.to_s.downcase}-#{@container.id}-attachments.zip")
+    end
+  end
+
   def update
     @attachment.safe_attributes = params[:attachment]
     saved = @attachment.save
@@ -195,6 +209,11 @@ class AttachmentsController < ApplicationController
   end
 
   def find_editable_attachments
+    @attachments = @container.attachments.select(&:editable?)
+    render_404 if @attachments.empty?
+  end
+
+  def find_container
     klass = params[:object_type].to_s.singularize.classify.constantize rescue nil
     unless klass && klass.reflect_on_association(:attachments)
       render_404
@@ -206,15 +225,24 @@ class AttachmentsController < ApplicationController
       render_403
       return
     end
-    @attachments = @container.attachments.select(&:editable?)
     if @container.respond_to?(:project)
       @project = @container.project
     end
-    render_404 if @attachments.empty?
   rescue ActiveRecord::RecordNotFound
     render_404
   end
 
+  def find_downloadable_attachments
+    @attachments = @container.attachments.select{|a| File.readable?(a.diskfile) }
+    bulk_download_max_size = Redmine::Configuration['bulk_download_max_size'].to_i.kilobytes
+    if @attachments.sum(&:filesize) > bulk_download_max_size
+      flash[:error] = l(:error_bulk_download_size_too_big,
+                        :max_size => bulk_download_max_size)
+      redirect_to back_url
+      return
+    end
+  end
+
   # Checks that the file exists and is readable
   def file_readable
     if @attachment.readable?
diff --git a/app/helpers/attachments_helper.rb b/app/helpers/attachments_helper.rb
index d03997c4b..700ec7fae 100644
--- a/app/helpers/attachments_helper.rb
+++ b/app/helpers/attachments_helper.rb
@@ -27,6 +27,10 @@ module AttachmentsHelper
     object_attachments_path container.class.name.underscore.pluralize, container.id
   end
 
+  def container_attachments_download_path(container)
+    object_attachments_download_path container.class.name.underscore.pluralize, container.id
+  end
+
   # Displays view/delete links to the attachments of the given object
   # Options:
   #   :author -- author names are not displayed if set to false
diff --git a/app/models/attachment.rb b/app/models/attachment.rb
index 627c1a181..b64bda9a5 100644
--- a/app/models/attachment.rb
+++ b/app/models/attachment.rb
@@ -19,6 +19,7 @@
 
 require "digest"
 require "fileutils"
+require "zip"
 
 class Attachment < ActiveRecord::Base
   include Redmine::SafeAttributes
@@ -345,6 +346,25 @@ class Attachment < ActiveRecord::Base
     Attachment.where("created_on < ? AND (container_type IS NULL OR container_type = '')", Time.now - age).destroy_all
   end
 
+  def self.attachments_to_zip(tmpfile, attachments)
+    attachments = attachments.select{|attachment| File.readable?(attachment.diskfile) }
+    return nil if attachments.blank?
+    Zip.unicode_names = true
+    existing_file_names = []
+    Zip::File.open(tmpfile.path, Zip::File::CREATE) do |zip|
+      attachments.each do |attachment|
+        filename = attachment.filename
+        existing_file_names << filename
+        # If a file with the same name already exists, change the file name.
+        if existing_file_names.count(filename) > 1
+          filename = "#{File.basename(filename, ".*")}(#{existing_file_names.count(filename)})#{File.extname(filename)}"
+        end
+        zip.add(filename, attachment.diskfile)
+      end
+    end
+    tmpfile
+  end
+
   # Moves an existing attachment to its target directory
   def move_to_target_directory!
     return unless !new_record? & readable?
diff --git a/app/views/attachments/_links.html.erb b/app/views/attachments/_links.html.erb
index 0a9f5e3eb..d4cad6d05 100644
--- a/app/views/attachments/_links.html.erb
+++ b/app/views/attachments/_links.html.erb
@@ -42,4 +42,13 @@
   </div>
   <% end %>
 <% end %>
+<% if attachments.size > 1 %>
+<div class="bulk-download">
+  <%= link_to(l(:label_download_all_attachments),
+  container_attachments_download_path(container),
+  :title => l(:label_download_all_attachments),
+  :class => 'icon icon-download'
+  ) %>
+</div>
+<% end %>
 </div>
diff --git a/config/configuration.yml.example b/config/configuration.yml.example
index a8b6be83c..54c3ab490 100644
--- a/config/configuration.yml.example
+++ b/config/configuration.yml.example
@@ -219,6 +219,9 @@ default:
   #avatar_server_url: https://www.gravatar.com        # default
   #avatar_server_url: https://seccdn.libravatar.org
 
+  # Upper limit of the total file size when bulk downloading attached files (KB)
+  # bulk_download_max_size: 512000
+
 # specific configuration options for production environment
 # that overrides the default ones
 production:
diff --git a/config/locales/en.yml b/config/locales/en.yml
index 3f0fd2d77..046d57238 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -211,6 +211,7 @@ en:
   error_unable_delete_issue_status: 'Unable to delete issue status (%{value})'
   error_unable_to_connect: "Unable to connect (%{value})"
   error_attachment_too_big: "This file cannot be uploaded because it exceeds the maximum allowed file size (%{max_size})"
+  error_bulk_download_size_too_big: "These attachments cannot be bulk downloaded because the total file size exceeds the maximum allowed size (%{max_size})"
   error_session_expired: "Your session has expired. Please login again."
   error_token_expired: "This password recovery link has expired, please try again."
   warning_attachments_not_saved: "%{count} file(s) could not be saved."
@@ -1015,6 +1016,7 @@ en:
   label_users_visibility_all: All active users
   label_users_visibility_members_of_visible_projects: Members of visible projects
   label_edit_attachments: Edit attached files
+  label_download_all_attachments: Download all attached files
   label_link_copied_issue: Link copied issue
   label_ask: Ask
   label_search_attachments_yes: Search attachment filenames and descriptions
diff --git a/config/locales/ja.yml b/config/locales/ja.yml
index dcd4598c4..0d74e9ff7 100644
--- a/config/locales/ja.yml
+++ b/config/locales/ja.yml
@@ -1016,6 +1016,7 @@ ja:
   button_export: エクスポート
   label_export_options: "%{export_format} エクスポート設定"
   error_attachment_too_big: このファイルはアップロードできません。添付ファイルサイズの上限(%{max_size})を超えています。
+  error_bulk_download_size_too_big: これらの添付ファイルをダウンロードできません。一括ダウンロードサイズの上限(%{max_size})を超えています。
   notice_failed_to_save_time_entries: "全%{total}件中%{count}件の作業時間が保存できませんでした: %{ids}。"
   label_x_issues:
     zero:  0 チケット
diff --git a/config/routes.rb b/config/routes.rb
index d8e5fd710..1ca659da1 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -289,6 +289,7 @@ Rails.application.routes.draw do
   resources :attachments, :only => [:show, :update, :destroy]
   get 'attachments/:object_type/:object_id/edit', :to => 'attachments#edit_all', :as => :object_attachments_edit
   patch 'attachments/:object_type/:object_id', :to => 'attachments#update_all', :as => :object_attachments
+  get 'attachments/:object_type/:object_id/download', :to => 'attachments#download_all', :as => :object_attachments_download
 
   resources :groups do
     resources :memberships, :controller => 'principal_memberships'
diff --git a/lib/redmine/configuration.rb b/lib/redmine/configuration.rb
index 1dfe8ddfc..ccbdd386a 100644
--- a/lib/redmine/configuration.rb
+++ b/lib/redmine/configuration.rb
@@ -24,7 +24,8 @@ module Redmine
     @defaults = {
       'avatar_server_url' => 'https://www.gravatar.com',
       'email_delivery' => nil,
-      'max_concurrent_ajax_uploads' => 2
+      'max_concurrent_ajax_uploads' => 2,
+      'bulk_download_max_size' => 512000
     }
 
     @config = nil
diff --git a/public/stylesheets/application.css b/public/stylesheets/application.css
index 815bd4e15..be03de53f 100644
--- a/public/stylesheets/application.css
+++ b/public/stylesheets/application.css
@@ -899,6 +899,8 @@ div.attachments p { margin:4px 0 2px 0; }
 div.attachments img { vertical-align: middle; }
 div.attachments span.author { font-size: 0.9em; color: #888; }
 
+div.bulk-download { margin-top: 1em; margin-left: 0.3em; margin-bottom: 0.4em;}
+
 div.thumbnails {margin:0.6em;}
 div.thumbnails div {background:#fff;border:2px solid #ddd;display:inline-block;margin-right:2px;}
 div.thumbnails img {margin: 3px; vertical-align: middle;}
diff --git a/test/functional/attachments_controller_test.rb b/test/functional/attachments_controller_test.rb
index bf889892d..235ec2c77 100644
--- a/test/functional/attachments_controller_test.rb
+++ b/test/functional/attachments_controller_test.rb
@@ -577,6 +577,50 @@ class AttachmentsControllerTest < Redmine::ControllerTest
     assert_equal 'This is a Ruby source file', attachment.description
   end
 
+  def test_download_all_with_valid_container
+    @request.session[:user_id] = 2
+    get :download_all, :params => {
+        :object_type => 'issues',
+        :object_id => '2'
+      }
+    assert_response 200
+    assert_equal response.headers['Content-Type'], 'application/zip'
+    assert_match (/issue-2-attachments.zip/), response.headers['Content-Disposition']
+    assert_not_includes Dir.entries(Rails.root.join('tmp')), /attachments_zip/
+  end
+
+  def test_download_all_with_invalid_container
+    @request.session[:user_id] = 2
+    get :download_all, :params => {
+        :object_type => 'issues',
+        :object_id => '999'
+      }
+    assert_response 404
+  end
+
+  def test_download_all_without_readable_attachments
+    @request.session[:user_id] = 2
+    get :download_all, :params => {
+        :object_type => 'issues',
+        :object_id => '1'
+      }
+    assert_equal Issue.find(1).attachments, []
+    assert_response 404
+  end
+
+  def test_download_all_with_maximum_bulk_download_size_larger_than_attachments
+    Redmine::Configuration.with 'bulk_download_max_size' => 0 do
+      @request.session[:user_id] = 2
+      get :download_all, :params => {
+          :object_type => 'issues',
+          :object_id => '2',
+          :back_url => '/issues/2'
+      }
+      assert_redirected_to '/issues/2'
+      assert_equal flash[:error], 'These attachments cannot be bulk downloaded because the total file size exceeds the maximum allowed size (0)'
+    end
+  end
+
   def test_destroy_issue_attachment
     set_tmp_attachments_directory
     issue = Issue.find(3)
diff --git a/test/unit/attachment_test.rb b/test/unit/attachment_test.rb
index 831278634..932266a9d 100644
--- a/test/unit/attachment_test.rb
+++ b/test/unit/attachment_test.rb
@@ -278,6 +278,36 @@ class AttachmentTest < ActiveSupport::TestCase
     end
   end
 
+  def test_attachments_to_zip_with_attachments
+    attachment = Attachment.create!(:file => uploaded_test_file("testfile.txt", ""), :author_id => 1)
+    Tempfile.create('attachments_zip', Rails.root.join('tmp')) do |tempfile|
+      zip_file = Attachment.attachments_to_zip(tempfile, [attachment])
+      assert_instance_of File, zip_file
+    end
+  end
+
+  def test_attachments_to_zip_without_attachments
+    Tempfile.create('attachments_zip', Rails.root.join('tmp')) do |tempfile|
+      zip_file = Attachment.attachments_to_zip(tempfile, [])
+      assert_nil zip_file
+    end
+  end
+
+  def test_attachments_to_zip_should_not_duplicate_file_names
+    attachment_1 = Attachment.create!(:file => uploaded_test_file("testfile.txt", ""), :author_id => 1)
+    attachment_2 = Attachment.create!(:file => uploaded_test_file("testfile.txt", ""), :author_id => 1)
+    Tempfile.create('attachments_zip', Rails.root.join('tmp')) do |tempfile|
+      zip_file = Attachment.attachments_to_zip(tempfile, [attachment_1, attachment_2])
+      zip_file_names = ['testfile.txt', 'testfile(2).txt']
+
+      Zip::File.open(zip_file.path) do |z|
+        z.each_with_index do |entry, i|
+          assert_includes zip_file_names[i], entry.name
+        end
+      end
+    end
+  end
+
   def test_move_from_root_to_target_directory_should_move_root_files
     a = Attachment.find(20)
     assert a.disk_directory.blank?
