diff --git a/app/assets/javascripts/lib/vue_resource.js.es6 b/app/assets/javascripts/lib/vue_resource.js.es6
new file mode 100644
index 0000000000000000000000000000000000000000..eff1dcabfa2d5b381b3c519711c9cc90f704f84a
--- /dev/null
+++ b/app/assets/javascripts/lib/vue_resource.js.es6
@@ -0,0 +1,2 @@
+//= require vue
+//= require vue-resource
diff --git a/app/assets/stylesheets/framework/variables.scss b/app/assets/stylesheets/framework/variables.scss
index 4baf6ee781afed05e3af2c59dce63b680a4b89b8..ee1c95fd373b9012c07697b3c73cee6e06641c31 100644
--- a/app/assets/stylesheets/framework/variables.scss
+++ b/app/assets/stylesheets/framework/variables.scss
@@ -56,6 +56,7 @@ $black-transparent: rgba(0, 0, 0, 0.3);
 $border-white-light: darken($white-light, $darken-border-factor);
 $border-white-normal: darken($white-normal, $darken-border-factor);
 
+$border-gray-light: darken($gray-light, $darken-border-factor);
 $border-gray-normal: darken($gray-normal, $darken-border-factor);
 $border-gray-dark: darken($white-normal, $darken-border-factor);
 
@@ -274,6 +275,7 @@ $dropdown-hover-color: #3b86ff;
 */
 $btn-active-gray: #ececec;
 $btn-active-gray-light: e4e7ed;
+$btn-white-active: #848484;
 
 /*
 * Badges
diff --git a/app/helpers/issuables_helper.rb b/app/helpers/issuables_helper.rb
index 1c213983a5bbcc9a510bb8c79487300ee4b1d979..e5bb8b93e7693e5d096949f66d855a6a0a5ecbd5 100644
--- a/app/helpers/issuables_helper.rb
+++ b/app/helpers/issuables_helper.rb
@@ -30,6 +30,15 @@ module IssuablesHelper
     end
   end
 
+  def serialize_issuable(issuable)
+    case issuable
+    when Issue
+      IssueSerializer.new.represent(issuable).to_json
+    when MergeRequest
+      MergeRequestSerializer.new.represent(issuable).to_json
+    end
+  end
+
   def template_dropdown_tag(issuable, &block)
     title = selected_template(issuable) || "Choose a template"
     options = {
diff --git a/app/models/concerns/issuable.rb b/app/models/concerns/issuable.rb
index 5e63825bf99f752eda2105e24325f5528d59ef9d..3517969eabc65b45ae612944c8e525df1ffffbc9 100644
--- a/app/models/concerns/issuable.rb
+++ b/app/models/concerns/issuable.rb
@@ -13,6 +13,7 @@ module Issuable
   include StripAttribute
   include Awardable
   include Taskable
+  include TimeTrackable
 
   included do
     cache_markdown_field :title, pipeline: :single_line
diff --git a/app/models/concerns/time_trackable.rb b/app/models/concerns/time_trackable.rb
new file mode 100644
index 0000000000000000000000000000000000000000..6fa2af4e4e6da2b863089edee20f588e3293ac3e
--- /dev/null
+++ b/app/models/concerns/time_trackable.rb
@@ -0,0 +1,58 @@
+# == TimeTrackable concern
+#
+# Contains functionality related to objects that support time tracking.
+#
+# Used by Issue and MergeRequest.
+#
+
+module TimeTrackable
+  extend ActiveSupport::Concern
+
+  included do
+    attr_reader :time_spent
+
+    alias_method :time_spent?, :time_spent
+
+    default_value_for :time_estimate, value: 0, allows_nil: false
+
+    has_many :timelogs, as: :trackable, dependent: :destroy
+  end
+
+  def spend_time(seconds, user)
+    return if seconds == 0
+
+    @time_spent = seconds
+    @time_spent_user = user
+
+    if seconds == :reset
+      reset_spent_time
+    else
+      add_or_subtract_spent_time
+    end
+  end
+
+  def total_time_spent
+    timelogs.sum(:time_spent)
+  end
+
+  def human_total_time_spent
+    Gitlab::TimeTrackingFormatter.output(total_time_spent)
+  end
+
+  def human_time_estimate
+    Gitlab::TimeTrackingFormatter.output(time_estimate)
+  end
+
+  private
+
+  def reset_spent_time
+    timelogs.new(time_spent: total_time_spent * -1, user: @time_spent_user)
+  end
+
+  def add_or_subtract_spent_time
+    # Exit if time to subtract exceeds the total time spent.
+    return if time_spent < 0 && (time_spent.abs > total_time_spent)
+
+    timelogs.new(time_spent: time_spent, user: @time_spent_user)
+  end
+end
diff --git a/app/models/timelog.rb b/app/models/timelog.rb
new file mode 100644
index 0000000000000000000000000000000000000000..f768c4e3da5da4531063367de6fea5ea3ebab0d3
--- /dev/null
+++ b/app/models/timelog.rb
@@ -0,0 +1,6 @@
+class Timelog < ActiveRecord::Base
+  validates :time_spent, :user, presence: true
+
+  belongs_to :trackable, polymorphic: true
+  belongs_to :user
+end
diff --git a/app/serializers/issuable_entity.rb b/app/serializers/issuable_entity.rb
index 17c9160cb197b5f4884ad2827075a08d48554d44..29aecb50849fce40bd630b01c80763e8a7ce8cbe 100644
--- a/app/serializers/issuable_entity.rb
+++ b/app/serializers/issuable_entity.rb
@@ -13,4 +13,8 @@ class IssuableEntity < Grape::Entity
   expose :created_at
   expose :updated_at
   expose :deleted_at
+  expose :time_estimate
+  expose :total_time_spent
+  expose :human_time_estimate
+  expose :human_total_time_spent
 end
diff --git a/app/services/issuable_base_service.rb b/app/services/issuable_base_service.rb
index 4ce5fd993d90290229c2544aca5af24abc8da54e..7491c256b998ed5f77a97b0540cb18612ed3858b 100644
--- a/app/services/issuable_base_service.rb
+++ b/app/services/issuable_base_service.rb
@@ -36,6 +36,14 @@ class IssuableBaseService < BaseService
     end
   end
 
+  def create_time_estimate_note(issuable)
+    SystemNoteService.change_time_estimate(issuable, issuable.project, current_user)
+  end
+
+  def create_time_spent_note(issuable)
+    SystemNoteService.change_time_spent(issuable, issuable.project, current_user)
+  end
+
   def filter_params(issuable)
     ability_name = :"admin_#{issuable.to_ability_name}"
 
@@ -156,6 +164,7 @@ class IssuableBaseService < BaseService
   def create(issuable)
     merge_slash_commands_into_params!(issuable)
     filter_params(issuable)
+    change_time_spent(issuable)
 
     params.delete(:state_event)
     params[:author] ||= current_user
@@ -198,13 +207,14 @@ class IssuableBaseService < BaseService
     change_subscription(issuable)
     change_todo(issuable)
     filter_params(issuable)
+    time_spent = change_time_spent(issuable)
     old_labels = issuable.labels.to_a
     old_mentioned_users = issuable.mentioned_users.to_a
 
     label_ids = process_label_ids(params, existing_label_ids: issuable.label_ids)
     params[:label_ids] = label_ids if labels_changing?(issuable.label_ids, label_ids)
 
-    if params.present? && update_issuable(issuable, params)
+    if (params.present? || time_spent) && update_issuable(issuable, params)
       # We do not touch as it will affect a update on updated_at field
       ActiveRecord::Base.no_touching do
         handle_common_system_notes(issuable, old_labels: old_labels)
@@ -251,6 +261,12 @@ class IssuableBaseService < BaseService
     end
   end
 
+  def change_time_spent(issuable)
+    time_spent = params.delete(:spend_time)
+
+    issuable.spend_time(time_spent, current_user) if time_spent
+  end
+
   def has_changes?(issuable, old_labels: [])
     valid_attrs = [:title, :description, :assignee_id, :milestone_id, :target_branch]
 
@@ -272,6 +288,14 @@ class IssuableBaseService < BaseService
       create_task_status_note(issuable)
     end
 
+    if issuable.previous_changes.include?('time_estimate')
+      create_time_estimate_note(issuable)
+    end
+
+    if issuable.time_spent?
+      create_time_spent_note(issuable)
+    end
+
     create_labels_note(issuable, old_labels) if issuable.labels != old_labels
   end
 end
diff --git a/app/services/slash_commands/interpret_service.rb b/app/services/slash_commands/interpret_service.rb
index d75c5b1800e5f3049495fba08e87dad6b1ec27fc..ea00415ae1fe5127a007231b98212ec44cba15f3 100644
--- a/app/services/slash_commands/interpret_service.rb
+++ b/app/services/slash_commands/interpret_service.rb
@@ -243,6 +243,53 @@ module SlashCommands
       @updates[:wip_event] = issuable.work_in_progress? ? 'unwip' : 'wip'
     end
 
+    desc 'Set time estimate'
+    params '<1w 3d 2h 14m>'
+    condition do
+      current_user.can?(:"admin_#{issuable.to_ability_name}", project)
+    end
+    command :estimate do |raw_duration|
+      time_estimate = Gitlab::TimeTrackingFormatter.parse(raw_duration)
+
+      if time_estimate
+        @updates[:time_estimate] = time_estimate
+      end
+    end
+
+    desc 'Add or substract spent time'
+    params '<1h 30m | -1h 30m>'
+    condition do
+      current_user.can?(:"admin_#{issuable.to_ability_name}", issuable)
+    end
+    command :spend do |raw_duration|
+      reduce_time = raw_duration.sub!(/\A-/, '')
+      time_spent = Gitlab::TimeTrackingFormatter.parse(raw_duration)
+
+      if time_spent
+        time_spent *= -1 if reduce_time
+
+        @updates[:spend_time] = time_spent
+      end
+    end
+
+    desc 'Remove time estimate'
+    condition do
+      issuable.persisted? &&
+        current_user.can?(:"admin_#{issuable.to_ability_name}", project)
+    end
+    command :remove_estimate do
+      @updates[:time_estimate] = 0
+    end
+
+    desc 'Remove spent time'
+    condition do
+      issuable.persisted? &&
+        current_user.can?(:"admin_#{issuable.to_ability_name}", project)
+    end
+    command :remove_time_spent do
+      @updates[:spend_time] = :reset
+    end
+
     # This is a dummy command, so that it appears in the autocomplete commands
     desc 'CC'
     params '@user'
diff --git a/app/services/system_note_service.rb b/app/services/system_note_service.rb
index 7613ecd5021cd4d7dd447f53c43ea80d5c0f622d..5ca2551ee61680821b317b311fb58164cfb647a4 100644
--- a/app/services/system_note_service.rb
+++ b/app/services/system_note_service.rb
@@ -109,6 +109,57 @@ module SystemNoteService
     create_note(noteable: noteable, project: project, author: author, note: body)
   end
 
+  # Called when the estimated time of a Noteable is changed
+  #
+  # noteable      - Noteable object
+  # project       - Project owning noteable
+  # author        - User performing the change
+  # time_estimate - Estimated time
+  #
+  # Example Note text:
+  #
+  #   "Changed estimate of this issue to 3d 5h"
+  #
+  # Returns the created Note object
+
+  def change_time_estimate(noteable, project, author)
+    parsed_time = Gitlab::TimeTrackingFormatter.output(noteable.time_estimate)
+    body = if noteable.time_estimate == 0
+             "Removed time estimate on this #{noteable.human_class_name}"
+           else
+             "Changed time estimate of this #{noteable.human_class_name} to #{parsed_time}"
+           end
+
+    create_note(noteable: noteable, project: project, author: author, note: body)
+  end
+
+  # Called when the spent time of a Noteable is changed
+  #
+  # noteable   - Noteable object
+  # project    - Project owning noteable
+  # author     - User performing the change
+  # time_spent - Spent time
+  #
+  # Example Note text:
+  #
+  #   "Added 2h 30m of time spent on this issue"
+  #
+  # Returns the created Note object
+
+  def change_time_spent(noteable, project, author)
+    time_spent = noteable.time_spent
+
+    if time_spent == :reset
+      body = "Removed time spent on this #{noteable.human_class_name}"
+    else
+      parsed_time = Gitlab::TimeTrackingFormatter.output(time_spent.abs)
+      action = time_spent > 0 ? 'Added' : 'Subtracted'
+      body = "#{action} #{parsed_time} of time spent on this #{noteable.human_class_name}"
+    end
+
+    create_note(noteable: noteable, project: project, author: author, note: body)
+  end
+
   # Called when the status of a Noteable is changed
   #
   # noteable - Noteable object
diff --git a/db/migrate/20161223034433_add_time_estimate_to_issuables.rb b/db/migrate/20161223034433_add_time_estimate_to_issuables.rb
new file mode 100644
index 0000000000000000000000000000000000000000..8d89756a9bcd6a3b7ca5b21f215faf1ae22f9b1d
--- /dev/null
+++ b/db/migrate/20161223034433_add_time_estimate_to_issuables.rb
@@ -0,0 +1,30 @@
+# See http://doc.gitlab.com/ce/development/migration_style_guide.html
+# for more information on how to write migrations for GitLab.
+
+class AddTimeEstimateToIssuables < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  # Set this constant to true if this migration requires downtime.
+  DOWNTIME = false
+
+  # When a migration requires downtime you **must** uncomment the following
+  # constant and define a short and easy to understand explanation as to why the
+  # migration requires downtime.
+  # DOWNTIME_REASON = ''
+
+  # When using the methods "add_concurrent_index" or "add_column_with_default"
+  # you must disable the use of transactions as these methods can not run in an
+  # existing transaction. When using "add_concurrent_index" make sure that this
+  # method is the _only_ method called in the migration, any other changes
+  # should go in a separate migration. This ensures that upon failure _only_ the
+  # index creation fails and can be retried or reverted easily.
+  #
+  # To disable transactions uncomment the following line and remove these
+  # comments:
+  # disable_ddl_transaction!
+
+  def change
+    add_column :issues, :time_estimate, :integer
+    add_column :merge_requests, :time_estimate, :integer
+  end
+end
diff --git a/db/migrate/20161223034646_create_timelogs.rb b/db/migrate/20161223034646_create_timelogs.rb
new file mode 100644
index 0000000000000000000000000000000000000000..d3353a67eec086123bb2b991dc5ee75d77e7b08f
--- /dev/null
+++ b/db/migrate/20161223034646_create_timelogs.rb
@@ -0,0 +1,38 @@
+# See http://doc.gitlab.com/ce/development/migration_style_guide.html
+# for more information on how to write migrations for GitLab.
+
+class CreateTimelogs < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  # Set this constant to true if this migration requires downtime.
+  DOWNTIME = false
+
+  # When a migration requires downtime you **must** uncomment the following
+  # constant and define a short and easy to understand explanation as to why the
+  # migration requires downtime.
+  # DOWNTIME_REASON = ''
+
+  # When using the methods "add_concurrent_index" or "add_column_with_default"
+  # you must disable the use of transactions as these methods can not run in an
+  # existing transaction. When using "add_concurrent_index" make sure that this
+  # method is the _only_ method called in the migration, any other changes
+  # should go in a separate migration. This ensures that upon failure _only_ the
+  # index creation fails and can be retried or reverted easily.
+  #
+  # To disable transactions uncomment the following line and remove these
+  # comments:
+  # disable_ddl_transaction!
+
+  def change
+    create_table :timelogs do |t|
+      t.integer :time_spent, null: false
+      t.references :trackable, polymorphic: true
+      t.references :user
+
+      t.timestamps null: false
+    end
+
+    add_index :timelogs, [:trackable_type, :trackable_id]
+    add_index :timelogs, :user_id
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index c58a886b0fa4ab019daab74353e77a2053d07fcd..7815392c1c3b84fb785ac5b182ba66e2ede806a8 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -506,6 +506,7 @@ ActiveRecord::Schema.define(version: 20170106172224) do
     t.integer "lock_version"
     t.text "title_html"
     t.text "description_html"
+    t.integer "time_estimate"
   end
 
   add_index "issues", ["assignee_id"], name: "index_issues_on_assignee_id", using: :btree
@@ -685,6 +686,7 @@ ActiveRecord::Schema.define(version: 20170106172224) do
     t.integer "lock_version"
     t.text "title_html"
     t.text "description_html"
+    t.integer "time_estimate"
   end
 
   add_index "merge_requests", ["assignee_id"], name: "index_merge_requests_on_assignee_id", using: :btree
@@ -1128,6 +1130,18 @@ ActiveRecord::Schema.define(version: 20170106172224) do
 
   add_index "tags", ["name"], name: "index_tags_on_name", unique: true, using: :btree
 
+  create_table "timelogs", force: :cascade do |t|
+    t.integer "time_spent", null: false
+    t.integer "trackable_id"
+    t.string "trackable_type"
+    t.integer "user_id"
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+  end
+
+  add_index "timelogs", ["trackable_type", "trackable_id"], name: "index_timelogs_on_trackable_type_and_trackable_id", using: :btree
+  add_index "timelogs", ["user_id"], name: "index_timelogs_on_user_id", using: :btree
+
   create_table "todos", force: :cascade do |t|
     t.integer "user_id", null: false
     t.integer "project_id", null: false
diff --git a/doc/user/project/slash_commands.md b/doc/user/project/slash_commands.md
index 5f6a6c6503e4e72adab1bcf163f987892476db32..87c9756ea5dac489f6a68658ac9dfcfe03f40b4d 100644
--- a/doc/user/project/slash_commands.md
+++ b/doc/user/project/slash_commands.md
@@ -29,3 +29,7 @@ do.
 | <code>/due &lt;in 2 days &#124; this Friday &#124; December 31st&gt;</code> | Set due date |
 | `/remove_due_date`         | Remove due date |
 | `/wip`                     | Toggle the Work In Progress status |
+| <code>/estimate &lt;1w 3d 2h 14m&gt;</code> | Set time estimate |
+| `/remove_estimate`       | Remove estimated time |
+| <code>/spend &lt;1h 30m &#124; -1h 5m&gt;</code> | Add or substract spent time |
+| `/remove_time_spent`       | Remove time spent |
diff --git a/doc/workflow/README.md b/doc/workflow/README.md
index 59a806de210f14d3985d23fc13522c4eb037b48e..b317bd79dedeffe2b0a34f1aeed320eb4074f258 100644
--- a/doc/workflow/README.md
+++ b/doc/workflow/README.md
@@ -19,6 +19,7 @@
 - [Slash commands](../user/project/slash_commands.md)
 - [Sharing a project with a group](share_with_group.md)
 - [Share projects with other groups](share_projects_with_other_groups.md)
+- [Time tracking](time_tracking.md)
 - [Web Editor](../user/project/repository/web_editor.md)
 - [Releases](releases.md)
 - [Milestones](milestones.md)
diff --git a/doc/workflow/time-tracking/time-tracking-example.png b/doc/workflow/time-tracking/time-tracking-example.png
new file mode 100644
index 0000000000000000000000000000000000000000..bbcabb602d67655043daa1b55bd37674642ba91a
Binary files /dev/null and b/doc/workflow/time-tracking/time-tracking-example.png differ
diff --git a/doc/workflow/time-tracking/time-tracking-sidebar.png b/doc/workflow/time-tracking/time-tracking-sidebar.png
new file mode 100644
index 0000000000000000000000000000000000000000..d1ff5571f95e7cd0d3bf284227727f3e2255e7ae
Binary files /dev/null and b/doc/workflow/time-tracking/time-tracking-sidebar.png differ
diff --git a/doc/workflow/time_tracking.md b/doc/workflow/time_tracking.md
new file mode 100644
index 0000000000000000000000000000000000000000..3b3103110d3c9a416275bf5292a1304ac366ade9
--- /dev/null
+++ b/doc/workflow/time_tracking.md
@@ -0,0 +1,76 @@
+# Time Tracking
+
+> Introduced in GitLab 8.14.
+
+Time Tracking lets teams stack their project estimates against their time spent.
+
+Other interesting links:
+
+- [Time Tracking landing page on about.gitlab.com][landing]
+
+## Overview
+
+Time Tracking lets you:
+* record the time spent working on an issue or a merge request,
+* add an estimate of the amount of time needed to complete an issue or a merge
+request.
+
+You don't have to indicate an estimate to enter the time spent, and vice versa.
+
+Data about time tracking is shown on the issue/merge request sidebar, as shown
+below.
+
+![Time tracking in the sidebar](time-tracking/time-tracking-sidebar.png)
+
+## How to enter data
+
+Time Tracking uses two [slash commands] that GitLab introduced with this new
+feature: `/spend` and `/estimate`.
+
+Slash commands can be used in the body of an issue or a merge request, but also
+in a comment in both an issue or a merge request.
+
+Below is an example of how you can use those new slash commands inside a comment.
+
+![Time tracking example in a comment](time-tracking/time-tracking-example.png)
+
+Adding time entries (time spent or estimates) is limited to project members.
+
+### Estimates
+
+To enter an estimate, write `/estimate`, followed by the time. For example, if
+you need to enter an estimate of 3 days, 5 hours and 10 minutes, you would write
+`/estimate 3d 5h 10m`.
+
+Every time you enter a new time estimate, any previous time estimates will be
+overridden by this new value. There should only be one valid estimate in an
+issue or a merge request.
+
+To remove an estimation entirely, use `/remove_estimation`.
+
+### Time spent
+
+To enter a time spent, use `/spend 3d 5h 10m`.
+
+Every new time spent entry will be added to the current total time spent for the
+issue or the merge request.
+
+You can remove time by entering a negative amount: `/spend -3d` will remove 3
+days from the total time spent. You can't go below 0 minutes of time spent,
+so GitLab will automatically reset the time spent if you remove a larger amount
+of time compared to the time that was entered already.
+
+To remove all the time spent at once, use `/remove_time_spent`.
+
+## Configuration
+
+The following time units are available:
+* weeks (w)
+* days (d)
+* hours (h)
+* minutes (m)
+
+Default conversion rates are 1w = 5d and 1d = 8h.
+
+[landing]: https://about.gitlab.com/features/time-tracking
+[slash-commands]: ../user/project/slash_commands.md
diff --git a/lib/gitlab/import_export/import_export.yml b/lib/gitlab/import_export/import_export.yml
index e6ecd11860999cdef08ad2c2d9b217419fa47249..08ad3274b3803f4155a8df3efa72e14deb01511f 100644
--- a/lib/gitlab/import_export/import_export.yml
+++ b/lib/gitlab/import_export/import_export.yml
@@ -6,6 +6,7 @@ project_tree:
     - :events
   - issues:
     - :events
+    - :timelogs
     - notes:
       - :author
       - :events
@@ -27,6 +28,7 @@ project_tree:
       - :events
     - :merge_request_diff
     - :events
+    - :timelogs
     - label_links:
       - label:
           :priorities
diff --git a/lib/gitlab/time_tracking_formatter.rb b/lib/gitlab/time_tracking_formatter.rb
new file mode 100644
index 0000000000000000000000000000000000000000..d09063c6c8f97a8568bacfb11c3f9b3c6ea2f822
--- /dev/null
+++ b/lib/gitlab/time_tracking_formatter.rb
@@ -0,0 +1,30 @@
+module Gitlab
+  module TimeTrackingFormatter
+    extend self
+
+    def parse(string)
+      with_custom_config do
+        ChronicDuration.parse(string, default_unit: 'hours') rescue nil
+      end
+    end
+
+    def output(seconds)
+      with_custom_config do
+        ChronicDuration.output(seconds, format: :short, limit_to_hours: false, weeks: true) rescue nil
+      end
+    end
+
+    def with_custom_config
+      # We may want to configure it through project settings in a future version.
+      ChronicDuration.hours_per_day = 8
+      ChronicDuration.days_per_week = 5
+
+      result = yield
+
+      ChronicDuration.hours_per_day = 24
+      ChronicDuration.days_per_week = 7
+
+      result
+    end
+  end
+end
diff --git a/spec/controllers/projects/issues_controller_spec.rb b/spec/controllers/projects/issues_controller_spec.rb
index e2321f2034b50eff8605eec211b83a96f7fb487b..b5987a83df0affcea451c4d78e8b718d97eda9af 100644
--- a/spec/controllers/projects/issues_controller_spec.rb
+++ b/spec/controllers/projects/issues_controller_spec.rb
@@ -326,6 +326,20 @@ describe Projects::IssuesController do
   end
 
   describe 'POST #create' do
+    def post_new_issue(attrs = {})
+      sign_in(user)
+      project = create(:empty_project, :public)
+      project.team << [user, :developer]
+
+      post :create, {
+        namespace_id: project.namespace.to_param,
+        project_id: project.to_param,
+        issue: { title: 'Title', description: 'Description' }.merge(attrs)
+      }
+
+      project.issues.first
+    end
+
     context 'resolving discussions in MergeRequest' do
       let(:discussion) { Discussion.for_diff_notes([create(:diff_note_on_merge_request)]).first }
       let(:merge_request) { discussion.noteable }
@@ -369,13 +383,7 @@ describe Projects::IssuesController do
       end
 
       def post_spam_issue
-        sign_in(user)
-        spam_project = create(:empty_project, :public)
-        post :create, {
-          namespace_id: spam_project.namespace.to_param,
-          project_id: spam_project.to_param,
-          issue: { title: 'Spam Title', description: 'Spam lives here' }
-        }
+        post_new_issue(title: 'Spam Title', description: 'Spam lives here')
       end
 
       it 'rejects an issue recognized as spam' do
@@ -396,18 +404,26 @@ describe Projects::IssuesController do
         request.env['action_dispatch.remote_ip'] = '127.0.0.1'
       end
 
-      def post_new_issue
+      it 'creates a user agent detail' do
+        expect{ post_new_issue }.to change(UserAgentDetail, :count).by(1)
+      end
+    end
+
+    context 'when description has slash commands' do
+      before do
         sign_in(user)
-        project = create(:empty_project, :public)
-        post :create, {
-          namespace_id: project.namespace.to_param,
-          project_id: project.to_param,
-          issue: { title: 'Title', description: 'Description' }
-        }
       end
 
-      it 'creates a user agent detail' do
-        expect{ post_new_issue }.to change(UserAgentDetail, :count).by(1)
+      it 'can add spent time' do
+        issue = post_new_issue(description: '/spend 1h')
+
+        expect(issue.total_time_spent).to eq(3600)
+      end
+
+      it 'can set the time estimate' do
+        issue = post_new_issue(description: '/estimate 2h')
+
+        expect(issue.time_estimate).to eq(7200)
       end
     end
   end
diff --git a/spec/factories/timelogs.rb b/spec/factories/timelogs.rb
new file mode 100644
index 0000000000000000000000000000000000000000..12fc4ec448634f523fd2be60435b1345d88d0be7
--- /dev/null
+++ b/spec/factories/timelogs.rb
@@ -0,0 +1,9 @@
+# Read about factories at https://github.com/thoughtbot/factory_girl
+
+FactoryGirl.define do
+  factory :timelog do
+    time_spent 3600
+    user
+    association :trackable, factory: :issue
+  end
+end
diff --git a/spec/features/issues/user_uses_slash_commands_spec.rb b/spec/features/issues/user_uses_slash_commands_spec.rb
index f2d4aadf5406414e470763d07cb4b53113b6a564..0a9cd11ad6e524eaae8d15a67217cba40dd4503f 100644
--- a/spec/features/issues/user_uses_slash_commands_spec.rb
+++ b/spec/features/issues/user_uses_slash_commands_spec.rb
@@ -126,6 +126,32 @@ feature 'Issues > User uses slash commands', feature: true, js: true do
       end
     end
 
+    describe 'Issuable time tracking' do
+      let(:issue) { create(:issue, project: project) }
+
+      before do
+        project.team << [user, :developer]
+      end
+
+      context 'Issue' do
+        before do
+          visit namespace_project_issue_path(project.namespace, project, issue)
+        end
+
+        it_behaves_like 'issuable time tracker'
+      end
+
+      context 'Merge Request' do
+        let(:merge_request) { create(:merge_request, source_project: project) }
+
+        before do
+          visit namespace_project_merge_request_path(project.namespace, project, merge_request)
+        end
+
+        it_behaves_like 'issuable time tracker'
+      end
+    end
+
     describe 'toggling the WIP prefix from the title from note' do
       let(:issue) { create(:issue, project: project) }
 
diff --git a/spec/lib/gitlab/import_export/all_models.yml b/spec/lib/gitlab/import_export/all_models.yml
index ceed9c942c11bddbedc517e0ea0bd86f512b7184..7fb6829f582f2514459b6644c05a0af35ade83a3 100644
--- a/spec/lib/gitlab/import_export/all_models.yml
+++ b/spec/lib/gitlab/import_export/all_models.yml
@@ -15,6 +15,7 @@ issues:
 - events
 - merge_requests_closing_issues
 - metrics
+- timelogs
 events:
 - author
 - project
@@ -77,6 +78,7 @@ merge_requests:
 - events
 - merge_requests_closing_issues
 - metrics
+- timelogs
 merge_request_diff:
 - merge_request
 pipelines:
@@ -198,3 +200,6 @@ award_emoji:
 - user
 priorities:
 - label
+timelogs:
+- trackable
+- user
diff --git a/spec/lib/gitlab/import_export/safe_model_attributes.yml b/spec/lib/gitlab/import_export/safe_model_attributes.yml
index d88a141b458ed5117bfa04d257d78aa23e8256ec..493bc2db21af108def3c04b6bb3fbac414a990e8 100644
--- a/spec/lib/gitlab/import_export/safe_model_attributes.yml
+++ b/spec/lib/gitlab/import_export/safe_model_attributes.yml
@@ -20,6 +20,7 @@ Issue:
 - lock_version
 - milestone_id
 - weight
+- time_estimate
 Event:
 - id
 - target_type
@@ -150,6 +151,7 @@ MergeRequest:
 - milestone_id
 - approvals_before_merge
 - rebase_commit_sha
+- time_estimate
 MergeRequestDiff:
 - id
 - state
@@ -344,3 +346,11 @@ LabelPriority:
 - priority
 - created_at
 - updated_at
+Timelog:
+- id
+- time_spent
+- trackable_id
+- trackable_type
+- user_id
+- created_at
+- updated_at
diff --git a/spec/models/concerns/issuable_spec.rb b/spec/models/concerns/issuable_spec.rb
index 1078c959419da528516b9c28b4c864a5e689436c..344906c581b57da060c33455c82ed4e2a0d3cd36 100644
--- a/spec/models/concerns/issuable_spec.rb
+++ b/spec/models/concerns/issuable_spec.rb
@@ -408,4 +408,42 @@ describe Issue, "Issuable" do
       expect(issue.assignee_or_author?(user)).to eq(false)
     end
   end
+
+  describe '#spend_time' do
+    let(:user) { create(:user) }
+    let(:issue) { create(:issue) }
+
+    def spend_time(seconds)
+      issue.spend_time(seconds, user)
+      issue.save!
+    end
+
+    context 'adding time' do
+      it 'should update the total time spent' do
+        spend_time(1800)
+
+        expect(issue.total_time_spent).to eq(1800)
+      end
+    end
+
+    context 'substracting time' do
+      before do
+        spend_time(1800)
+      end
+
+      it 'should update the total time spent' do
+        spend_time(-900)
+
+        expect(issue.total_time_spent).to eq(900)
+      end
+
+      context 'when time to substract exceeds the total time spent' do
+        it 'should not alter the total time spent' do
+          spend_time(-3600)
+
+          expect(issue.total_time_spent).to eq(1800)
+        end
+      end
+    end
+  end
 end
diff --git a/spec/models/timelog_spec.rb b/spec/models/timelog_spec.rb
new file mode 100644
index 0000000000000000000000000000000000000000..f08935b64254c7154702f9ca767c0ba2f913e1c3
--- /dev/null
+++ b/spec/models/timelog_spec.rb
@@ -0,0 +1,10 @@
+require 'rails_helper'
+
+RSpec.describe Timelog, type: :model do
+  subject { build(:timelog) }
+
+  it { is_expected.to be_valid }
+
+  it { is_expected.to validate_presence_of(:time_spent) }
+  it { is_expected.to validate_presence_of(:user) }
+end
diff --git a/spec/services/notes/slash_commands_service_spec.rb b/spec/services/notes/slash_commands_service_spec.rb
index 960b5cd5e6fca8ca6af7e17cf9d95af9e102f132..1a64c8bbf00df05a396be79b356f8b73afa3e3ef 100644
--- a/spec/services/notes/slash_commands_service_spec.rb
+++ b/spec/services/notes/slash_commands_service_spec.rb
@@ -86,6 +86,18 @@ describe Notes::SlashCommandsService, services: true do
           expect(note.noteable).to be_open
         end
       end
+
+      describe '/spend' do
+        let(:note_text) { '/spend 1h' }
+
+        it 'updates the spent time on the noteable' do
+          content, command_params = service.extract_commands(note)
+          service.execute(command_params, note)
+
+          expect(content).to eq ''
+          expect(note.noteable.time_spent).to eq(3600)
+        end
+      end
     end
 
     describe 'note with command & text' do
diff --git a/spec/services/slash_commands/interpret_service_spec.rb b/spec/services/slash_commands/interpret_service_spec.rb
index becf627a4f582cf20cd0c735fb48246025a9dd67..e1358acd7c14e345e9794c5b2ee03c3c6fb1f529 100644
--- a/spec/services/slash_commands/interpret_service_spec.rb
+++ b/spec/services/slash_commands/interpret_service_spec.rb
@@ -210,6 +210,46 @@ describe SlashCommands::InterpretService, services: true do
       end
     end
 
+    shared_examples 'estimate command' do
+      it 'populates time_estimate: 3600 if content contains /estimate 1h' do
+        _, updates = service.execute(content, issuable)
+
+        expect(updates).to eq(time_estimate: 3600)
+      end
+    end
+
+    shared_examples 'spend command' do
+      it 'populates spend_time: 3600 if content contains /spend 1h' do
+        _, updates = service.execute(content, issuable)
+
+        expect(updates).to eq(spend_time: 3600)
+      end
+    end
+
+    shared_examples 'spend command with negative time' do
+      it 'populates spend_time: -1800 if content contains /spend -30m' do
+        _, updates = service.execute(content, issuable)
+
+        expect(updates).to eq(spend_time: -1800)
+      end
+    end
+
+    shared_examples 'remove_estimate command' do
+      it 'populates time_estimate: 0 if content contains /remove_estimate' do
+        _, updates = service.execute(content, issuable)
+
+        expect(updates).to eq(time_estimate: 0)
+      end
+    end
+
+    shared_examples 'remove_time_spent command' do
+      it 'populates spend_time: :reset if content contains /remove_time_spent' do
+        _, updates = service.execute(content, issuable)
+
+        expect(updates).to eq(spend_time: :reset)
+      end
+    end
+
     shared_examples 'empty command' do
       it 'populates {} if content contains an unsupported command' do
         _, updates = service.execute(content, issuable)
@@ -451,6 +491,51 @@ describe SlashCommands::InterpretService, services: true do
       let(:issuable) { merge_request }
     end
 
+    it_behaves_like 'estimate command' do
+      let(:content) { '/estimate 1h' }
+      let(:issuable) { issue }
+    end
+
+    it_behaves_like 'empty command' do
+      let(:content) { '/estimate' }
+      let(:issuable) { issue }
+    end
+
+    it_behaves_like 'empty command' do
+      let(:content) { '/estimate abc' }
+      let(:issuable) { issue }
+    end
+
+    it_behaves_like 'spend command' do
+      let(:content) { '/spend 1h' }
+      let(:issuable) { issue }
+    end
+
+    it_behaves_like 'spend command with negative time' do
+      let(:content) { '/spend -30m' }
+      let(:issuable) { issue }
+    end
+
+    it_behaves_like 'empty command' do
+      let(:content) { '/spend' }
+      let(:issuable) { issue }
+    end
+
+    it_behaves_like 'empty command' do
+      let(:content) { '/spend abc' }
+      let(:issuable) { issue }
+    end
+
+    it_behaves_like 'remove_estimate command' do
+      let(:content) { '/remove_estimate' }
+      let(:issuable) { issue }
+    end
+
+    it_behaves_like 'remove_time_spent command' do
+      let(:content) { '/remove_time_spent' }
+      let(:issuable) { issue }
+    end
+
     context 'when current_user cannot :admin_issue' do
       let(:visitor) { create(:user) }
       let(:issue) { create(:issue, project: project, author: visitor) }
diff --git a/spec/services/system_note_service_spec.rb b/spec/services/system_note_service_spec.rb
index 0e8adb687212bd1149c986788b0e079c584dc4ad..e85545f46dc4d684c085d642fbe30a8252ca995e 100644
--- a/spec/services/system_note_service_spec.rb
+++ b/spec/services/system_note_service_spec.rb
@@ -740,4 +740,69 @@ describe SystemNoteService, services: true do
       expect(note.note).to include(issue.to_reference)
     end
   end
+
+  describe '.change_time_estimate' do
+    subject { described_class.change_time_estimate(noteable, project, author) }
+
+    it_behaves_like 'a system note'
+
+    context 'with a time estimate' do
+      it 'sets the note text' do
+        noteable.update_attribute(:time_estimate, 277200)
+
+        expect(subject.note).to eq "Changed time estimate of this issue to 1w 4d 5h"
+      end
+    end
+
+    context 'without a time estimate' do
+      it 'sets the note text' do
+        expect(subject.note).to eq "Removed time estimate on this issue"
+      end
+    end
+  end
+
+  describe '.change_time_spent' do
+    # We need a custom noteable in order to the shared examples to be green.
+    let(:noteable) do
+      mr = create(:merge_request, source_project: project)
+      mr.spend_time(1, author)
+      mr.save!
+      mr
+    end
+
+    subject do
+      described_class.change_time_spent(noteable, project, author)
+    end
+
+    it_behaves_like 'a system note'
+
+    context 'when time was added' do
+      it 'sets the note text' do
+        spend_time!(277200)
+
+        expect(subject.note).to eq "Added 1w 4d 5h of time spent on this merge request"
+      end
+    end
+
+    context 'when time was subtracted' do
+      it 'sets the note text' do
+        spend_time!(-277200)
+
+        expect(subject.note).to eq "Subtracted 1w 4d 5h of time spent on this merge request"
+      end
+    end
+
+    context 'when time was removed' do
+      it 'sets the note text' do
+        spend_time!(:reset)
+
+        expect(subject.note).to eq "Removed time spent on this merge request"
+      end
+    end
+
+    def spend_time!(seconds)
+      noteable.spend_time(seconds, author)
+      noteable.save!
+    end
+  end
 end