diff --git a/Library/Homebrew/cask/lib/hbc/auditor.rb b/Library/Homebrew/cask/lib/hbc/auditor.rb
index 6b0c1c4764373..ee1b50938b75b 100644
--- a/Library/Homebrew/cask/lib/hbc/auditor.rb
+++ b/Library/Homebrew/cask/lib/hbc/auditor.rb
@@ -1,6 +1,23 @@
 module Hbc
   class Auditor
     def self.audit(cask, audit_download: false, check_token_conflicts: false)
+      saved_languages = MacOS.instance_variable_get(:@languages)
+
+      if languages_blocks = cask.instance_variable_get(:@dsl).instance_variable_get(:@language_blocks)
+        languages_blocks.keys.each do |languages|
+          ohai "Auditing language: #{languages.map { |lang| "'#{lang}'" }.join(", ")}"
+          MacOS.instance_variable_set(:@languages, languages)
+          audit_cask_instance(Hbc.load(cask.sourcefile_path), audit_download, check_token_conflicts)
+          CLI::Cleanup.run(cask.token) if audit_download
+        end
+      else
+        audit_cask_instance(cask, audit_download, check_token_conflicts)
+      end
+    ensure
+      MacOS.instance_variable_set(:@languages, saved_languages)
+    end
+
+    def self.audit_cask_instance(cask, audit_download, check_token_conflicts)
       download = audit_download && Download.new(cask)
       audit = Audit.new(cask, download:              download,
                               check_token_conflicts: check_token_conflicts)
diff --git a/Library/Homebrew/cask/lib/hbc/cask.rb b/Library/Homebrew/cask/lib/hbc/cask.rb
index 756b05b83fcb7..1e2056efc705e 100644
--- a/Library/Homebrew/cask/lib/hbc/cask.rb
+++ b/Library/Homebrew/cask/lib/hbc/cask.rb
@@ -11,7 +11,10 @@ def initialize(token, sourcefile_path: nil, dsl: nil, &block)
       @token = token
       @sourcefile_path = sourcefile_path
       @dsl = dsl || DSL.new(@token)
-      @dsl.instance_eval(&block) if block_given?
+      if block_given?
+        @dsl.instance_eval(&block)
+        @dsl.language_eval
+      end
     end
 
     DSL::DSL_METHODS.each do |method_name|
diff --git a/Library/Homebrew/cask/lib/hbc/cli.rb b/Library/Homebrew/cask/lib/hbc/cli.rb
index 3f67e131ddc1c..f637ae7af5f72 100644
--- a/Library/Homebrew/cask/lib/hbc/cli.rb
+++ b/Library/Homebrew/cask/lib/hbc/cli.rb
@@ -179,6 +179,10 @@ def self.nice_listing(cask_list)
     def self.parser
       # If you modify these arguments, please update USAGE.md
       @parser ||= OptionParser.new do |opts|
+        opts.on("--language STRING") do
+          # handled in OS::Mac
+        end
+
         OPTIONS.each do |option, method|
           opts.on("#{option}" "PATH", Pathname) do |path|
             Hbc.public_send(method, path)
diff --git a/Library/Homebrew/cask/lib/hbc/dsl.rb b/Library/Homebrew/cask/lib/hbc/dsl.rb
index 83c0bf1fb3316..8e0a7715af427 100644
--- a/Library/Homebrew/cask/lib/hbc/dsl.rb
+++ b/Library/Homebrew/cask/lib/hbc/dsl.rb
@@ -1,4 +1,5 @@
 require "set"
+require "locale"
 
 require "hbc/dsl/appcast"
 require "hbc/dsl/base"
@@ -64,6 +65,7 @@ class DSL
                             :depends_on,
                             :gpg,
                             :homepage,
+                            :language,
                             :license,
                             :name,
                             :sha256,
@@ -98,6 +100,43 @@ def homepage(homepage = nil)
       @homepage ||= homepage
     end
 
+    def language(*args, default: false, &block)
+      if !args.empty? && block_given?
+        @language_blocks ||= {}
+        @language_blocks[args] = block
+
+        return unless default
+
+        unless @language_blocks.default.nil?
+          raise CaskInvalidError.new(token, "Only one default language may be defined")
+        end
+
+        @language_blocks.default = block
+      else
+        language_eval
+      end
+    end
+
+    def language_eval
+      return @language if instance_variable_defined?(:@language)
+
+      if @language_blocks.nil? || @language_blocks.empty?
+        return @language = nil
+      end
+
+      MacOS.languages.map(&Locale.method(:parse)).each do |locale|
+        key = @language_blocks.keys.detect { |strings|
+          strings.any? { |string| locale.include?(string) }
+        }
+
+        next if key.nil?
+
+        return @language = @language_blocks[key].call
+      end
+
+      @language = @language_blocks.default.call
+    end
+
     def url(*args, &block)
       url_given = !args.empty? || block_given?
       return @url unless url_given
diff --git a/Library/Homebrew/cask/lib/hbc/dsl/base.rb b/Library/Homebrew/cask/lib/hbc/dsl/base.rb
index ccf93dae9a213..20a3cec619baa 100644
--- a/Library/Homebrew/cask/lib/hbc/dsl/base.rb
+++ b/Library/Homebrew/cask/lib/hbc/dsl/base.rb
@@ -8,7 +8,7 @@ def initialize(cask, command = SystemCommand)
         @command = command
       end
 
-      def_delegators :@cask, :token, :version, :caskroom_path, :staged_path, :appdir
+      def_delegators :@cask, :token, :version, :caskroom_path, :staged_path, :appdir, :language
 
       def system_command(executable, options = {})
         @command.run!(executable, options)
diff --git a/Library/Homebrew/cask/spec/locale_spec.rb b/Library/Homebrew/cask/spec/locale_spec.rb
new file mode 100644
index 0000000000000..98a2de9139469
--- /dev/null
+++ b/Library/Homebrew/cask/spec/locale_spec.rb
@@ -0,0 +1,72 @@
+require "spec_helper"
+require "locale"
+
+describe Locale do
+  describe "::parse" do
+    it "parses a string in the correct format" do
+      expect(described_class.parse("zh")).to eql(described_class.new("zh", nil, nil))
+      expect(described_class.parse("zh-CN")).to eql(described_class.new("zh", "CN", nil))
+      expect(described_class.parse("zh-Hans")).to eql(described_class.new("zh", nil, "Hans"))
+      expect(described_class.parse("zh-CN-Hans")).to eql(described_class.new("zh", "CN", "Hans"))
+    end
+
+    context "raises a ParserError when given" do
+      it "an empty string" do
+        expect{ described_class.parse("") }.to raise_error(Locale::ParserError)
+      end
+
+      it "a string in a wrong format" do
+        expect { described_class.parse("zh_CN_Hans") }.to raise_error(Locale::ParserError)
+        expect { described_class.parse("zhCNHans") }.to raise_error(Locale::ParserError)
+        expect { described_class.parse("zh-CN_Hans") }.to raise_error(Locale::ParserError)
+        expect { described_class.parse("zhCN") }.to raise_error(Locale::ParserError)
+        expect { described_class.parse("zh_Hans") }.to raise_error(Locale::ParserError)
+      end
+    end
+  end
+
+  describe "::new" do
+    it "raises an ArgumentError when all arguments are nil" do
+      expect { described_class.new(nil, nil, nil) }.to raise_error(ArgumentError)
+    end
+
+    it "raises a ParserError when one of the arguments does not match the locale format" do
+      expect { described_class.new("ZH", nil, nil) }.to raise_error(Locale::ParserError)
+      expect { described_class.new(nil, "cn", nil) }.to raise_error(Locale::ParserError)
+      expect { described_class.new(nil, nil, "hans") }.to raise_error(Locale::ParserError)
+    end
+  end
+
+  subject { described_class.new("zh", "CN", "Hans") }
+
+  describe "#include?" do
+    it { is_expected.to include("zh") }
+    it { is_expected.to include("zh-CN") }
+    it { is_expected.to include("CN") }
+    it { is_expected.to include("CN-Hans") }
+    it { is_expected.to include("Hans") }
+    it { is_expected.to include("zh-CN-Hans") }
+  end
+
+  describe "#eql?" do
+    subject { described_class.new("zh", "CN", "Hans") }
+
+    context "all parts match" do
+      it { is_expected.to eql("zh-CN-Hans") }
+      it { is_expected.to eql(subject) }
+    end
+
+    context "only some parts match" do
+      it { is_expected.to_not eql("zh") }
+      it { is_expected.to_not eql("zh-CN") }
+      it { is_expected.to_not eql("CN") }
+      it { is_expected.to_not eql("CN-Hans") }
+      it { is_expected.to_not eql("Hans") }
+    end
+
+    it "does not raise if 'other' cannot be parsed" do
+      expect { subject.eql?("zh_CN_Hans") }.not_to raise_error
+      expect(subject.eql?("zh_CN_Hans")).to be false
+    end
+  end
+end
diff --git a/Library/Homebrew/cask/test/cask/dsl_test.rb b/Library/Homebrew/cask/test/cask/dsl_test.rb
index ccf2f1a24816f..053eae1e1dd11 100644
--- a/Library/Homebrew/cask/test/cask/dsl_test.rb
+++ b/Library/Homebrew/cask/test/cask/dsl_test.rb
@@ -122,6 +122,56 @@
     end
   end
 
+  describe "language stanza" do
+    it "allows multilingual casks" do
+      cask = lambda do
+        Hbc::Cask.new("cask-with-apps") do
+          language "zh" do
+            sha256 "abc123"
+            "zh-CN"
+          end
+
+          language "en-US", default: true do
+            sha256 "xyz789"
+            "en-US"
+          end
+
+          url "https://example.org/#{language}.zip"
+        end
+      end
+
+      MacOS.stubs(languages: ["zh"])
+      cask.call.language.must_equal "zh-CN"
+      cask.call.sha256.must_equal "abc123"
+      cask.call.url.to_s.must_equal "https://example.org/zh-CN.zip"
+
+      MacOS.stubs(languages: ["zh-XX"])
+      cask.call.language.must_equal "zh-CN"
+      cask.call.sha256.must_equal "abc123"
+      cask.call.url.to_s.must_equal "https://example.org/zh-CN.zip"
+
+      MacOS.stubs(languages: ["en"])
+      cask.call.language.must_equal "en-US"
+      cask.call.sha256.must_equal "xyz789"
+      cask.call.url.to_s.must_equal "https://example.org/en-US.zip"
+
+      MacOS.stubs(languages: ["xx-XX"])
+      cask.call.language.must_equal "en-US"
+      cask.call.sha256.must_equal "xyz789"
+      cask.call.url.to_s.must_equal "https://example.org/en-US.zip"
+
+      MacOS.stubs(languages: ["xx-XX", "zh", "en"])
+      cask.call.language.must_equal "zh-CN"
+      cask.call.sha256.must_equal "abc123"
+      cask.call.url.to_s.must_equal "https://example.org/zh-CN.zip"
+
+      MacOS.stubs(languages: ["xx-XX", "en-US", "zh"])
+      cask.call.language.must_equal "en-US"
+      cask.call.sha256.must_equal "xyz789"
+      cask.call.url.to_s.must_equal "https://example.org/en-US.zip"
+    end
+  end
+
   describe "app stanza" do
     it "allows you to specify app stanzas" do
       cask = Hbc::Cask.new("cask-with-apps") do
diff --git a/Library/Homebrew/locale.rb b/Library/Homebrew/locale.rb
new file mode 100644
index 0000000000000..1aff33dae6c8b
--- /dev/null
+++ b/Library/Homebrew/locale.rb
@@ -0,0 +1,68 @@
+class Locale
+  class ParserError < ::RuntimeError
+  end
+
+  LANGUAGE_REGEX = /(?:[a-z]{2})/
+  REGION_REGEX = /(?:[A-Z]{2})/
+  SCRIPT_REGEX = /(?:[A-Z][a-z]{3})/
+
+  LOCALE_REGEX = /^(#{LANGUAGE_REGEX})?(?:(?:^|-)(#{REGION_REGEX}))?(?:(?:^|-)(#{SCRIPT_REGEX}))?$/
+
+  def self.parse(string)
+    language, region, script = string.to_s.scan(LOCALE_REGEX)[0]
+
+    if language.nil? && region.nil? && script.nil?
+      raise ParserError, "'#{string}' cannot be parsed to a #{self.class}"
+    end
+
+    new(language, region, script)
+  end
+
+  attr_reader :language, :region, :script
+
+  def initialize(language, region, script)
+    if language.nil? && region.nil? && script.nil?
+      raise ArgumentError, "#{self.class} cannot be empty"
+    end
+
+    {
+      language: language,
+      region:   region,
+      script:   script,
+    }.each do |key, value|
+      next if value.nil?
+
+      regex = self.class.const_get("#{key.upcase}_REGEX")
+      raise ParserError, "'#{value}' does not match #{regex}" unless value =~ regex
+      instance_variable_set(:"@#{key}", value)
+    end
+
+    self
+  end
+
+  def include?(other)
+    other = self.class.parse(other) unless other.is_a?(self.class)
+
+    [:language, :region, :script].all? { |var|
+      if other.public_send(var).nil?
+        true
+      else
+        public_send(var) == other.public_send(var)
+      end
+    }
+  end
+
+  def eql?(other)
+    other = self.class.parse(other) unless other.is_a?(self.class)
+    [:language, :region, :script].all? { |var|
+      public_send(var) == other.public_send(var)
+    }
+  rescue ParserError
+    false
+  end
+  alias == eql?
+
+  def to_s
+    [@language, @region, @script].compact.join("-")
+  end
+end
diff --git a/Library/Homebrew/os/mac.rb b/Library/Homebrew/os/mac.rb
index 0b01478253f1c..b2f0515a0a2bd 100644
--- a/Library/Homebrew/os/mac.rb
+++ b/Library/Homebrew/os/mac.rb
@@ -41,8 +41,24 @@ def cat
       version.to_sym
     end
 
+    def languages
+      return @languages unless @languages.nil?
+
+      @languages = Utils.popen_read("defaults", "read", ".GlobalPreferences", "AppleLanguages").scan(/[^ \n"(),]+/)
+
+      if ENV["HOMEBREW_LANGUAGES"]
+        @languages = ENV["HOMEBREW_LANGUAGES"].split(",") + @languages
+      end
+
+      if ARGV.value("language")
+        @languages = ARGV.value("language").split(",") + @languages
+      end
+
+      @languages = @languages.uniq
+    end
+
     def language
-      @language ||= Utils.popen_read("defaults", "read", ".GlobalPreferences", "AppleLanguages").delete(" \n\"()").sub(/,.*/, "")
+      languages.first
     end
 
     def active_developer_dir
diff --git a/Library/Homebrew/test/test_os_mac_language.rb b/Library/Homebrew/test/test_os_mac_language.rb
index 2cdd50917da18..709913000bb98 100644
--- a/Library/Homebrew/test/test_os_mac_language.rb
+++ b/Library/Homebrew/test/test_os_mac_language.rb
@@ -2,7 +2,15 @@
 require "os/mac"
 
 class OSMacLanguageTests < Homebrew::TestCase
+  LANGUAGE_REGEX = /\A[a-z]{2}(-[A-Z]{2})?(-[A-Z][a-z]{3})?\Z/
+
+  def test_languages_format
+    OS::Mac.languages.each do |language|
+      assert_match LANGUAGE_REGEX, language
+    end
+  end
+
   def test_language_format
-    assert_match(/\A[a-z]{2}(-[A-Z]{2})?\Z/, OS::Mac.language)
+    assert_match LANGUAGE_REGEX, OS::Mac.language
   end
 end