diff --git a/Library/Homebrew/brew.rb b/Library/Homebrew/brew.rb
index 7b05186e8c..17a008a778 100644
--- a/Library/Homebrew/brew.rb
+++ b/Library/Homebrew/brew.rb
@@ -50,7 +50,7 @@ begin
   help_flag = !ENV["HOMEBREW_HELP"].nil?
   cmd = nil
 
-  ARGV.dup.each_with_index do |arg, i|
+  ARGV.each_with_index do |arg, i|
     break if help_flag && cmd
 
     if arg == "help" && !cmd
diff --git a/Library/Homebrew/cask/auditor.rb b/Library/Homebrew/cask/auditor.rb
index 844fa8d9ee..db3cfa7317 100644
--- a/Library/Homebrew/cask/auditor.rb
+++ b/Library/Homebrew/cask/auditor.rb
@@ -38,7 +38,7 @@ module Cask
     end
 
     def audit
-      if !ARGV.value("language") && language_blocks
+      if !Homebrew.args.value("language") && language_blocks
         audit_all_languages
       else
         audit_cask_instance(cask)
diff --git a/Library/Homebrew/cli/args.rb b/Library/Homebrew/cli/args.rb
index 7d9f940d7c..ac5fd1875b 100644
--- a/Library/Homebrew/cli/args.rb
+++ b/Library/Homebrew/cli/args.rb
@@ -10,7 +10,7 @@ module Homebrew
       # undefine tap to allow --tap argument
       undef tap
 
-      def initialize(argv = ARGV.dup.freeze, set_default_args: false)
+      def initialize(argv = ARGV.freeze, set_default_args: false)
         super()
 
         @processed_options = []
@@ -177,6 +177,14 @@ module Homebrew
         formulae.any? { |args_f| args_f.full_name == f.full_name }
       end
 
+      def value(name)
+        arg_prefix = "--#{name}="
+        flag_with_value = flags_only.find { |arg| arg.start_with?(arg_prefix) }
+        return unless flag_with_value
+
+        flag_with_value.delete_prefix(arg_prefix)
+      end
+
       private
 
       def option_to_name(option)
diff --git a/Library/Homebrew/cli/parser.rb b/Library/Homebrew/cli/parser.rb
index 5486f464b8..8109bceee1 100644
--- a/Library/Homebrew/cli/parser.rb
+++ b/Library/Homebrew/cli/parser.rb
@@ -13,7 +13,7 @@ module Homebrew
     class Parser
       attr_reader :processed_options, :hide_from_man_page
 
-      def self.parse(argv = ARGV.dup.freeze, allow_no_named_args: false, &block)
+      def self.parse(argv = ARGV.freeze, allow_no_named_args: false, &block)
         new(argv, &block).parse(allow_no_named_args: allow_no_named_args)
       end
 
@@ -38,7 +38,7 @@ module Homebrew
         }
       end
 
-      def initialize(argv = ARGV.dup.freeze, &block)
+      def initialize(argv = ARGV.freeze, &block)
         @parser = OptionParser.new
         @argv = argv
         @args = Homebrew::CLI::Args.new(@argv)
diff --git a/Library/Homebrew/dev-cmd/irb.rb b/Library/Homebrew/dev-cmd/irb.rb
index 56c164ec5f..e748e6fa19 100644
--- a/Library/Homebrew/dev-cmd/irb.rb
+++ b/Library/Homebrew/dev-cmd/irb.rb
@@ -19,7 +19,7 @@ module Homebrew
 
   def irb_args
     # work around IRB modifying ARGV.
-    Homebrew::CLI::Parser.new(ARGV.dup) do
+    Homebrew::CLI::Parser.new(ARGV.dup.freeze) do
       usage_banner <<~EOS
         `irb` [<options>]
 
diff --git a/Library/Homebrew/extend/ARGV.rb b/Library/Homebrew/extend/ARGV.rb
deleted file mode 100644
index 7e28311296..0000000000
--- a/Library/Homebrew/extend/ARGV.rb
+++ /dev/null
@@ -1,9 +0,0 @@
-# frozen_string_literal: true
-
-module HomebrewArgvExtension
-  def value(name)
-    arg_prefix = "--#{name}="
-    flag_with_value = find { |arg| arg.start_with?(arg_prefix) }
-    flag_with_value&.delete_prefix(arg_prefix)
-  end
-end
diff --git a/Library/Homebrew/formula_installer.rb b/Library/Homebrew/formula_installer.rb
index b5f3bc7746..da998b9e43 100644
--- a/Library/Homebrew/formula_installer.rb
+++ b/Library/Homebrew/formula_installer.rb
@@ -746,7 +746,7 @@ class FormulaInstaller
 
     formula.options.each do |opt|
       name = opt.name[/^([^=]+)=$/, 1]
-      value = ARGV.value(name) if name
+      value = Homebrew.args.value(name) if name
       args << "--#{name}=#{value}" if value
     end
 
diff --git a/Library/Homebrew/global.rb b/Library/Homebrew/global.rb
index b7067e7717..dbdca9a57c 100644
--- a/Library/Homebrew/global.rb
+++ b/Library/Homebrew/global.rb
@@ -35,13 +35,10 @@ require "env_config"
 
 require "config"
 require "os"
-require "extend/ARGV"
 require "cli/args"
 require "messages"
 require "system_command"
 
-ARGV.extend(HomebrewArgvExtension)
-
 HOMEBREW_PRODUCT = ENV["HOMEBREW_PRODUCT"]
 HOMEBREW_VERSION = ENV["HOMEBREW_VERSION"]
 HOMEBREW_WWW = "https://brew.sh"
diff --git a/Library/Homebrew/os/linux.rb b/Library/Homebrew/os/linux.rb
index b295005c3a..c035191168 100644
--- a/Library/Homebrew/os/linux.rb
+++ b/Library/Homebrew/os/linux.rb
@@ -42,11 +42,7 @@ module OS
     end
 
     def languages
-      @languages ||= [
-        *ARGV.value("language")&.split(","),
-        *ENV["HOMEBREW_LANGUAGES"]&.split(","),
-        *ENV["LANG"]&.slice(/[a-z]+/),
-      ].uniq
+      @languages ||= [*ENV["LANG"]&.slice(/[a-z]+/)].uniq
     end
 
     def language
diff --git a/Library/Homebrew/os/mac.rb b/Library/Homebrew/os/mac.rb
index 3118edf50f..4e77f0cf25 100644
--- a/Library/Homebrew/os/mac.rb
+++ b/Library/Homebrew/os/mac.rb
@@ -60,9 +60,11 @@ module OS
 
     def languages
       @languages ||= [
-        *ARGV.value("language")&.split(","),
+        *Homebrew.args.value("language")&.split(","),
         *ENV["HOMEBREW_LANGUAGES"]&.split(","),
-        *Open3.capture2("defaults", "read", "-g", "AppleLanguages")[0].scan(/[^ \n"(),]+/),
+        *Open3.capture2("defaults", "read", "-g", "AppleLanguages")
+              .first
+              .scan(/[^ \n"(),]+/),
       ].uniq
     end
 
diff --git a/Library/Homebrew/test/ARGV_spec.rb b/Library/Homebrew/test/ARGV_spec.rb
deleted file mode 100644
index 01adb3a52f..0000000000
--- a/Library/Homebrew/test/ARGV_spec.rb
+++ /dev/null
@@ -1,22 +0,0 @@
-# frozen_string_literal: true
-
-require "extend/ARGV"
-
-describe HomebrewArgvExtension do
-  subject { argv.extend(described_class) }
-
-  let(:argv) { ["mxcl"] }
-
-  describe "#value" do
-    let(:argv) { ["--foo=", "--bar=ab"] }
-
-    it "returns the value for a given string" do
-      expect(subject.value("foo")).to eq ""
-      expect(subject.value("bar")).to eq "ab"
-    end
-
-    it "returns nil if there is no matching argument" do
-      expect(subject.value("baz")).to be nil
-    end
-  end
-end
diff --git a/Library/Homebrew/test/formula_installer_spec.rb b/Library/Homebrew/test/formula_installer_spec.rb
index 53fd117e03..cf15e5ba1a 100644
--- a/Library/Homebrew/test/formula_installer_spec.rb
+++ b/Library/Homebrew/test/formula_installer_spec.rb
@@ -48,8 +48,6 @@ describe FormulaInstaller do
   end
 
   specify "basic installation" do
-    ARGV << "--with-invalid_flag" # added to ensure it doesn't fail install
-
     temporary_install(Testball.new) do |f|
       # Test that things made it into the Keg
       expect(f.prefix/"readme").to exist
diff --git a/Library/Homebrew/test/spec_helper.rb b/Library/Homebrew/test/spec_helper.rb
index f40e98cb25..fc3fbd8387 100644
--- a/Library/Homebrew/test/spec_helper.rb
+++ b/Library/Homebrew/test/spec_helper.rb
@@ -172,7 +172,6 @@ RSpec.configure do |config|
 
       @__files_before_test = find_files
 
-      @__argv = ARGV.dup
       @__env = ENV.to_hash # dup doesn't work on ENV
 
       @__stdout = $stdout.clone
@@ -187,7 +186,6 @@ RSpec.configure do |config|
     rescue SystemExit => e
       raise "Unexpected exit with status #{e.status}."
     ensure
-      ARGV.replace(@__argv)
       ENV.replace(@__env)
 
       $stdout.reopen(@__stdout)
diff --git a/Library/Homebrew/test/utils/bottles/collector_spec.rb b/Library/Homebrew/test/utils/bottles/collector_spec.rb
index 91a1a25b34..5df7bd45a5 100644
--- a/Library/Homebrew/test/utils/bottles/collector_spec.rb
+++ b/Library/Homebrew/test/utils/bottles/collector_spec.rb
@@ -35,7 +35,7 @@ describe Utils::Bottles::Collector do
     end
 
     it "ignores HOMEBREW_SKIP_OR_LATER_BOTTLES on release versions", :needs_macos do
-      allow(ARGV).to receive(:skip_or_later_bottles?).and_return(true)
+      allow(Homebrew::EnvConfig).to receive(:skip_or_later_bottles?).and_return(true)
       allow(OS::Mac).to receive(:prerelease?).and_return(false)
       subject[:mavericks] = "foo"
       expect(subject.send(:find_matching_tag, :mavericks)).to eq(:mavericks)
diff --git a/Library/Homebrew/utils/bottles.rb b/Library/Homebrew/utils/bottles.rb
index c886ae1c2f..250cb00126 100644
--- a/Library/Homebrew/utils/bottles.rb
+++ b/Library/Homebrew/utils/bottles.rb
@@ -1,7 +1,6 @@
 # frozen_string_literal: true
 
 require "tab"
-require "extend/ARGV"
 
 module Utils
   class Bottles