diff --git a/Library/Homebrew/cask/audit.rb b/Library/Homebrew/cask/audit.rb
index db019bda75..fbaff98c80 100644
--- a/Library/Homebrew/cask/audit.rb
+++ b/Library/Homebrew/cask/audit.rb
@@ -17,12 +17,12 @@ module Cask
 
     attr_predicate :appcast?
 
-    def initialize(cask, appcast: false, download: false,
+    def initialize(cask, appcast: false, download: false, quarantine: nil,
                    token_conflicts: false, online: false, strict: false,
                    new_cask: false, commit_range: nil, command: SystemCommand)
       @cask = cask
       @appcast = appcast
-      @download = download
+      @download = Download.new(cask, quarantine: quarantine) if download
       @online = online
       @strict = strict
       @new_cask = new_cask
diff --git a/Library/Homebrew/cask/auditor.rb b/Library/Homebrew/cask/auditor.rb
index 4f209120dc..7abc4bb2c6 100644
--- a/Library/Homebrew/cask/auditor.rb
+++ b/Library/Homebrew/cask/auditor.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require "cask/download"
-
 module Cask
   class Auditor
     include Checkable
@@ -51,28 +49,26 @@ module Cask
     private
 
     def audit_all_languages
-      saved_languages = MacOS.instance_variable_get(:@languages)
-      begin
-        language_blocks.keys.all?(&method(:audit_languages))
-      ensure
-        MacOS.instance_variable_set(:@languages, saved_languages)
-      end
+      language_blocks.keys.all?(&method(:audit_languages))
     end
 
     def audit_languages(languages)
       ohai "Auditing language: #{languages.map { |lang| "'#{lang}'" }.to_sentence}"
-      MacOS.instance_variable_set(:@languages, languages)
-      audit_cask_instance(CaskLoader.load(cask.sourcefile_path))
+      localized_cask = CaskLoader.load(cask.sourcefile_path)
+      config = localized_cask.config
+      config.languages = languages
+      localized_cask.config = config
+      audit_cask_instance(localized_cask)
     end
 
     def audit_cask_instance(cask)
-      download = audit_download? && Download.new(cask, quarantine: quarantine?)
       audit = Audit.new(cask, appcast:         audit_appcast?,
                               online:          audit_online?,
                               strict:          audit_strict?,
                               new_cask:        audit_new_cask?,
                               token_conflicts: audit_token_conflicts?,
-                              download:        download,
+                              download:        audit_download?,
+                              quarantine:      quarantine?,
                               commit_range:    commit_range)
       audit.run!
       puts audit.summary
diff --git a/Library/Homebrew/cask/cmd.rb b/Library/Homebrew/cask/cmd.rb
index 139e063887..60abf6580a 100644
--- a/Library/Homebrew/cask/cmd.rb
+++ b/Library/Homebrew/cask/cmd.rb
@@ -65,8 +65,7 @@ module Cask
 
     option "--help", :help, false
 
-    # handled in OS::Mac
-    option "--language a,b,c", ->(*) {}
+    option "--language=a,b,c", ->(value) { Config.global.languages = value }
 
     # override default handling of --version
     option "--version", ->(*) { raise OptionParser::InvalidOption }
@@ -180,8 +179,6 @@ module Cask
     end
 
     def process_options(*args)
-      exclude_regex = /^--#{Regexp.union(*Config::DEFAULT_DIRS.keys.map(&Regexp.public_method(:escape)))}=/
-
       non_options = []
 
       if idx = args.index("--")
@@ -189,15 +186,31 @@ module Cask
         args = args.first(idx)
       end
 
+      exclude_regex = /^--#{Regexp.union(*Config::DEFAULT_DIRS.keys.map(&Regexp.public_method(:escape)))}=/
       cask_opts = Shellwords.shellsplit(ENV.fetch("HOMEBREW_CASK_OPTS", ""))
                             .reject { |arg| arg.match?(exclude_regex) }
 
       all_args = cask_opts + args
 
-      remaining = all_args.select do |arg|
-        !process_arguments([arg]).empty?
-      rescue OptionParser::InvalidOption, OptionParser::MissingArgument, OptionParser::AmbiguousOption
-        true
+      i = 0
+      remaining = []
+
+      while i < all_args.count
+        begin
+          arg = all_args[i]
+
+          remaining << arg unless process_arguments([arg]).empty?
+        rescue OptionParser::MissingArgument
+          raise if i + 1 >= all_args.count
+
+          args = all_args[i..(i + 1)]
+          process_arguments(args)
+          i += 1
+        rescue OptionParser::InvalidOption
+          remaining << arg
+        end
+
+        i += 1
       end
 
       remaining + non_options
diff --git a/Library/Homebrew/cask/config.rb b/Library/Homebrew/cask/config.rb
index bd9bd71155..74c68bc243 100644
--- a/Library/Homebrew/cask/config.rb
+++ b/Library/Homebrew/cask/config.rb
@@ -2,6 +2,9 @@
 
 require "json"
 
+require "lazy_object"
+require "locale"
+
 require "extend/hash_validator"
 using HashValidator
 
@@ -24,6 +27,12 @@ module Cask
       screen_saverdir:      "~/Library/Screen Savers",
     }.freeze
 
+    def self.defaults
+      {
+        languages: LazyObject.new { MacOS.languages },
+      }.merge(DEFAULT_DIRS).freeze
+    end
+
     def self.global
       @global ||= new
     end
@@ -69,16 +78,16 @@ module Cask
     attr_accessor :explicit
 
     def initialize(default: nil, env: nil, explicit: {})
-      @default = self.class.canonicalize(DEFAULT_DIRS.merge(default)) if default
+      @default = self.class.canonicalize(self.class.defaults.merge(default)) if default
       @env = self.class.canonicalize(env) if env
       @explicit = self.class.canonicalize(explicit)
 
-      @env&.assert_valid_keys!(*DEFAULT_DIRS.keys)
-      @explicit.assert_valid_keys!(*DEFAULT_DIRS.keys)
+      @env&.assert_valid_keys!(*self.class.defaults.keys)
+      @explicit.assert_valid_keys!(*self.class.defaults.keys)
     end
 
     def default
-      @default ||= self.class.canonicalize(DEFAULT_DIRS)
+      @default ||= self.class.canonicalize(self.class.defaults)
     end
 
     def env
@@ -86,7 +95,16 @@ module Cask
         Shellwords.shellsplit(ENV.fetch("HOMEBREW_CASK_OPTS", ""))
                   .select { |arg| arg.include?("=") }
                   .map { |arg| arg.split("=", 2) }
-                  .map { |(flag, value)| [flag.sub(/^--/, ""), value] },
+                  .map do |(flag, value)|
+                    key = flag.sub(/^--/, "")
+
+                    if key == "language"
+                      key = "languages"
+                      value = value.split(",")
+                    end
+
+                    [key, value]
+                  end,
       )
     end
 
@@ -98,6 +116,24 @@ module Cask
       @manpagedir ||= HOMEBREW_PREFIX/"share/man"
     end
 
+    def languages
+      [
+        *explicit[:languages],
+        *env[:languages],
+        *default[:languages],
+      ].uniq.select do |lang|
+        # Ensure all languages are valid.
+        Locale.parse(lang)
+        true
+      rescue Locale::ParserError
+        false
+      end
+    end
+
+    def languages=(languages)
+      explicit[:languages] = languages
+    end
+
     DEFAULT_DIRS.each_key do |dir|
       define_method(dir) do
         explicit.fetch(dir, env.fetch(dir, default.fetch(dir)))
diff --git a/Library/Homebrew/cask/dsl.rb b/Library/Homebrew/cask/dsl.rb
index 525f927a2f..87b83e8d3f 100644
--- a/Library/Homebrew/cask/dsl.rb
+++ b/Library/Homebrew/cask/dsl.rb
@@ -137,13 +137,13 @@ module Cask
 
       raise CaskInvalidError.new(cask, "No default language specified.") if @language_blocks.default.nil?
 
-      locales = MacOS.languages
-                     .map do |language|
-                       Locale.parse(language)
-                     rescue Locale::ParserError
-                       nil
-                     end
-                     .compact
+      locales = cask.config.languages
+                    .map do |language|
+                      Locale.parse(language)
+                    rescue Locale::ParserError
+                      nil
+                    end
+                    .compact
 
       locales.each do |locale|
         key = locale.detect(@language_blocks.keys)
@@ -225,7 +225,7 @@ module Cask
     end
 
     def caskroom_path
-      @cask.caskroom_path
+      cask.caskroom_path
     end
 
     def staged_path
diff --git a/Library/Homebrew/os/mac.rb b/Library/Homebrew/os/mac.rb
index 8a854ab01f..b44a47bcc4 100644
--- a/Library/Homebrew/os/mac.rb
+++ b/Library/Homebrew/os/mac.rb
@@ -68,21 +68,7 @@ module OS
       end
       os_langs = os_langs.scan(/[^ \n"(),]+/)
 
-      @languages = [
-        *Homebrew.args.value("language")&.split(","),
-        *ENV["HOMEBREW_LANGUAGES"]&.split(","),
-        *os_langs,
-      ].uniq
-
-      # Ensure all languages are valid
-      @languages.select! do |lang|
-        Locale.parse(lang)
-        true
-      rescue Locale::ParserError
-        false
-      end
-
-      @languages
+      @languages = os_langs
     end
 
     def language
diff --git a/Library/Homebrew/test/cask/audit_spec.rb b/Library/Homebrew/test/cask/audit_spec.rb
index 122913370b..3ddfdcc7ea 100644
--- a/Library/Homebrew/test/cask/audit_spec.rb
+++ b/Library/Homebrew/test/cask/audit_spec.rb
@@ -15,16 +15,6 @@ describe Cask::Audit, :cask do
     end
   end
 
-  matcher :fail do
-    match(&:errors?)
-  end
-
-  matcher :warn do
-    match do |audit|
-      audit.warnings? && !audit.errors?
-    end
-  end
-
   matcher :fail_with do |error_msg|
     match do |audit|
       include_msg?(audit.errors, error_msg)
@@ -764,23 +754,27 @@ describe Cask::Audit, :cask do
     describe "audit of downloads" do
       let(:cask_token) { "with-binary" }
       let(:cask) { Cask::CaskLoader.load(cask_token) }
-      let(:download) { instance_double(Cask::Download) }
+      let(:download_double) { instance_double(Cask::Download) }
       let(:verify) { class_double(Cask::Verify).as_stubbed_const }
       let(:error_msg) { "Download Failed" }
 
+      before do
+        allow(audit).to receive(:download).and_return(download_double)
+      end
+
       it "when download and verification succeed it does not fail" do
-        expect(download).to receive(:perform)
+        expect(download_double).to receive(:perform)
         expect(verify).to receive(:all)
         expect(subject).not_to fail_with(/#{error_msg}/)
       end
 
       it "when download fails it does not fail" do
-        expect(download).to receive(:perform).and_raise(StandardError.new(error_msg))
+        expect(download_double).to receive(:perform).and_raise(StandardError.new(error_msg))
         expect(subject).to fail_with(/#{error_msg}/)
       end
 
       it "when verification fails it does not fail" do
-        expect(download).to receive(:perform)
+        expect(download_double).to receive(:perform)
         expect(verify).to receive(:all).and_raise(StandardError.new(error_msg))
         expect(subject).to fail_with(/#{error_msg}/)
       end
diff --git a/Library/Homebrew/test/cask/cmd_spec.rb b/Library/Homebrew/test/cask/cmd_spec.rb
index bd6b9d9795..6e5c3be828 100644
--- a/Library/Homebrew/test/cask/cmd_spec.rb
+++ b/Library/Homebrew/test/cask/cmd_spec.rb
@@ -15,12 +15,6 @@ describe Cask::Cmd, :cask do
                           ])
   end
 
-  it "ignores the `--language` option, which is handled in `OS::Mac`" do
-    cli = described_class.new("--language=en")
-    expect(cli).to receive(:detect_internal_command).with(no_args)
-    cli.run
-  end
-
   context "when given no arguments" do
     it "exits successfully" do
       expect(subject).not_to receive(:exit).with(be_nonzero)
diff --git a/Library/Homebrew/test/cask/dsl_spec.rb b/Library/Homebrew/test/cask/dsl_spec.rb
index 24b4a06dc2..949a1c804f 100644
--- a/Library/Homebrew/test/cask/dsl_spec.rb
+++ b/Library/Homebrew/test/cask/dsl_spec.rb
@@ -118,8 +118,8 @@ describe Cask::DSL, :cask do
   end
 
   describe "language stanza" do
-    it "allows multilingual casks" do
-      cask = lambda do
+    context "when language is set explicitly" do
+      subject(:cask) {
         Cask::Cask.new("cask-with-apps") do
           language "zh" do
             sha256 "abc123"
@@ -133,37 +133,65 @@ describe Cask::DSL, :cask do
 
           url "https://example.org/#{language}.zip"
         end
+      }
+
+      matcher :be_the_chinese_version do
+        match do |cask|
+          expect(cask.language).to eq("zh-CN")
+          expect(cask.sha256).to eq("abc123")
+          expect(cask.url.to_s).to eq("https://example.org/zh-CN.zip")
+        end
       end
 
-      allow(MacOS).to receive(:languages).and_return(["zh"])
-      expect(cask.call.language).to eq("zh-CN")
-      expect(cask.call.sha256).to eq("abc123")
-      expect(cask.call.url.to_s).to eq("https://example.org/zh-CN.zip")
+      matcher :be_the_english_version do
+        match do |cask|
+          expect(cask.language).to eq("en-US")
+          expect(cask.sha256).to eq("xyz789")
+          expect(cask.url.to_s).to eq("https://example.org/en-US.zip")
+        end
+      end
 
-      allow(MacOS).to receive(:languages).and_return(["zh-XX"])
-      expect(cask.call.language).to eq("zh-CN")
-      expect(cask.call.sha256).to eq("abc123")
-      expect(cask.call.url.to_s).to eq("https://example.org/zh-CN.zip")
+      before do
+        config = cask.config
+        config.languages = languages
+        cask.config = config
+      end
 
-      allow(MacOS).to receive(:languages).and_return(["en"])
-      expect(cask.call.language).to eq("en-US")
-      expect(cask.call.sha256).to eq("xyz789")
-      expect(cask.call.url.to_s).to eq("https://example.org/en-US.zip")
+      context "to 'zh'" do
+        let(:languages) { ["zh"] }
 
-      allow(MacOS).to receive(:languages).and_return(["xx-XX"])
-      expect(cask.call.language).to eq("en-US")
-      expect(cask.call.sha256).to eq("xyz789")
-      expect(cask.call.url.to_s).to eq("https://example.org/en-US.zip")
+        it { is_expected.to be_the_chinese_version }
+      end
 
-      allow(MacOS).to receive(:languages).and_return(["xx-XX", "zh", "en"])
-      expect(cask.call.language).to eq("zh-CN")
-      expect(cask.call.sha256).to eq("abc123")
-      expect(cask.call.url.to_s).to eq("https://example.org/zh-CN.zip")
+      context "to 'zh-XX'" do
+        let(:languages) { ["zh-XX"] }
 
-      allow(MacOS).to receive(:languages).and_return(["xx-XX", "en-US", "zh"])
-      expect(cask.call.language).to eq("en-US")
-      expect(cask.call.sha256).to eq("xyz789")
-      expect(cask.call.url.to_s).to eq("https://example.org/en-US.zip")
+        it { is_expected.to be_the_chinese_version }
+      end
+
+      context "to 'en'" do
+        let(:languages) { ["en"] }
+
+        it { is_expected.to be_the_english_version }
+      end
+
+      context "to 'xx-XX'" do
+        let(:languages) { ["xx-XX"] }
+
+        it { is_expected.to be_the_english_version }
+      end
+
+      context "to 'xx-XX,zh,en'" do
+        let(:languages) { ["xx-XX", "zh", "en"] }
+
+        it { is_expected.to be_the_chinese_version }
+      end
+
+      context "to 'xx-XX,en-US,zh'" do
+        let(:languages) { ["xx-XX", "en-US", "zh"] }
+
+        it { is_expected.to be_the_english_version }
+      end
     end
 
     it "returns an empty array if no languages are specified" do
diff --git a/Library/Homebrew/test/cmd/readall_spec.rb b/Library/Homebrew/test/cmd/readall_spec.rb
index 03f3b2ae5c..00a740c5f6 100644
--- a/Library/Homebrew/test/cmd/readall_spec.rb
+++ b/Library/Homebrew/test/cmd/readall_spec.rb
@@ -6,7 +6,7 @@ describe "Homebrew.readall_args" do
   it_behaves_like "parseable arguments"
 end
 
-describe "brew readall", :integration_test do
+describe "brew readall", :integration_test, timeout: 180 do
   it "imports all Formulae for a given Tap" do
     formula_file = setup_test_formula "testball"
 
diff --git a/Library/Homebrew/test/os/mac_spec.rb b/Library/Homebrew/test/os/mac_spec.rb
index dcb04a77a8..e3c1aa8cbb 100644
--- a/Library/Homebrew/test/os/mac_spec.rb
+++ b/Library/Homebrew/test/os/mac_spec.rb
@@ -5,10 +5,8 @@ require "os/mac"
 
 describe OS::Mac do
   describe "::languages" do
-    specify "all languages can be parsed by Locale::parse" do
-      subject.languages.each do |language|
-        expect { Locale.parse(language) }.not_to raise_error
-      end
+    it "returns a list of all languages" do
+      expect(subject.languages).not_to be_empty
     end
   end
 
@@ -16,10 +14,6 @@ describe OS::Mac do
     it "returns the first item from #languages" do
       expect(subject.language).to eq(subject.languages.first)
     end
-
-    it "can be parsed by Locale::parse" do
-      expect { Locale.parse(subject.language) }.not_to raise_error
-    end
   end
 
   describe "::sdk_path_if_needed" do
diff --git a/Library/Homebrew/test/spec_helper.rb b/Library/Homebrew/test/spec_helper.rb
index 337569b431..9e6ee3e826 100644
--- a/Library/Homebrew/test/spec_helper.rb
+++ b/Library/Homebrew/test/spec_helper.rb
@@ -29,6 +29,7 @@ require "rubocop"
 require "rubocop/rspec/support"
 require "find"
 require "byebug"
+require "timeout"
 
 $LOAD_PATH.push(File.expand_path("#{ENV["HOMEBREW_LIBRARY"]}/Homebrew/test/support/lib"))
 
@@ -181,7 +182,19 @@ RSpec.configure do |config|
         $stderr.reopen(File::NULL)
       end
 
-      example.run
+      begin
+        timeout = example.metadata.fetch(:timeout, 60)
+        inner_timeout = nil
+        Timeout.timeout(timeout) do
+          example.run
+        rescue Timeout::Error => e
+          inner_timeout = e
+        end
+      rescue Timeout::Error
+        raise "Example exceeded maximum runtime of #{timeout} seconds."
+      end
+
+      raise inner_timeout if inner_timeout
     rescue SystemExit => e
       raise "Unexpected exit with status #{e.status}."
     ensure