diff --git a/.gitignore b/.gitignore
index 7f978ca750f96..55a5659a8436c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -21,6 +21,7 @@
 /Library/Taps
 /Library/PinnedTaps
 /Library/Homebrew/.byebug_history
+/Library/Homebrew/test/.rdbg_history
 
 # Ignore Bundler files
 **/.bundle/bin
@@ -105,6 +106,7 @@
 **/vendor/bundle/ruby/*/gems/racc-*/
 **/vendor/bundle/ruby/*/gems/rainbow-*/
 **/vendor/bundle/ruby/*/gems/rbi-*/
+**/vendor/bundle/ruby/*/gems/rdoc-*/
 **/vendor/bundle/ruby/*/gems/regexp_parser-*/
 **/vendor/bundle/ruby/*/gems/rexml-*/
 **/vendor/bundle/ruby/*/gems/rspec-*/
diff --git a/Library/Homebrew/Gemfile b/Library/Homebrew/Gemfile
index 86fc80f2dd189..533593a96f489 100644
--- a/Library/Homebrew/Gemfile
+++ b/Library/Homebrew/Gemfile
@@ -48,7 +48,6 @@ group :style, optional: true do
   gem "rubocop-sorbet", require: false
 end
 group :tests, optional: true do
-  gem "byebug", require: false
   gem "parallel_tests", require: false
   gem "rspec", require: false
   gem "rspec-github", require: false
diff --git a/Library/Homebrew/Gemfile.lock b/Library/Homebrew/Gemfile.lock
index 04970dc6c7f80..04018f866b453 100644
--- a/Library/Homebrew/Gemfile.lock
+++ b/Library/Homebrew/Gemfile.lock
@@ -7,7 +7,6 @@ GEM
     bindata (2.5.0)
     bootsnap (1.18.3)
       msgpack (~> 1.2)
-    byebug (11.1.3)
     coderay (1.1.3)
     commander (4.6.0)
       highline (~> 2.0.0)
@@ -167,7 +166,6 @@ PLATFORMS
 DEPENDENCIES
   addressable
   bootsnap
-  byebug
   json_schemer
   kramdown
   method_source
diff --git a/Library/Homebrew/dev-cmd/tests.rb b/Library/Homebrew/dev-cmd/tests.rb
index d3d5e547862ce..0a3a99b2d19e7 100644
--- a/Library/Homebrew/dev-cmd/tests.rb
+++ b/Library/Homebrew/dev-cmd/tests.rb
@@ -21,8 +21,8 @@ class Tests < AbstractCommand
         switch "--online",
                description: "Include tests that use the GitHub API and tests that use any of the taps for " \
                             "official external commands."
-        switch "--byebug",
-               description: "Enable debugging using byebug."
+        switch "--debug",
+               description: "Enable debugging using ruby/debug, or surface the standard `odebug` output."
         switch "--changed",
                description: "Only runs tests on files that were changed from the master branch."
         switch "--fail-fast",
@@ -45,8 +45,6 @@ def run
         # Given we might be testing various commands, we probably want everything (except sorbet-static)
         Homebrew.install_bundler_gems!(groups: Homebrew.valid_gem_groups - ["sorbet"])
 
-        require "byebug" if args.byebug?
-
         HOMEBREW_LIBRARY_PATH.cd do
           setup_environment!
 
@@ -137,6 +135,8 @@ def run
 
           puts "Randomized with seed #{seed}"
 
+          ENV["HOMEBREW_DEBUG"] = "1" if args.debug? # Used in spec_helper.rb to require the "debug" gem.
+
           # Submit test flakiness information using BuildPulse
           # BUILDPULSE used in spec_helper.rb
           if use_buildpulse?
diff --git a/Library/Homebrew/sorbet/rbi/dsl/homebrew/dev_cmd/tests.rbi b/Library/Homebrew/sorbet/rbi/dsl/homebrew/dev_cmd/tests.rbi
index 61a59f02ee333..821f583831241 100644
--- a/Library/Homebrew/sorbet/rbi/dsl/homebrew/dev_cmd/tests.rbi
+++ b/Library/Homebrew/sorbet/rbi/dsl/homebrew/dev_cmd/tests.rbi
@@ -5,9 +5,6 @@
 # Please instead update this file by running `bin/tapioca dsl Homebrew::DevCmd::Tests`.
 
 class Homebrew::CLI::Args
-  sig { returns(T::Boolean) }
-  def byebug?; end
-
   sig { returns(T::Boolean) }
   def changed?; end
 
diff --git a/Library/Homebrew/sorbet/tapioca/config.yml b/Library/Homebrew/sorbet/tapioca/config.yml
index f94af4c19f89f..027f3e0ce2dcb 100644
--- a/Library/Homebrew/sorbet/tapioca/config.yml
+++ b/Library/Homebrew/sorbet/tapioca/config.yml
@@ -6,7 +6,6 @@ gem:
     - json
     - msgpack
     # These aren't needed:
-    - byebug
     - coderay
     - commander
     - diff-lcs
diff --git a/Library/Homebrew/standalone/init.rb b/Library/Homebrew/standalone/init.rb
index fafbaa2ab576c..7e3d2f04f996a 100644
--- a/Library/Homebrew/standalone/init.rb
+++ b/Library/Homebrew/standalone/init.rb
@@ -39,6 +39,14 @@
   ENV["HOMEBREW_SKIP_INITIAL_GEM_INSTALL"] = "1"
 end
 
+if Pathname.new(RbConfig.ruby).to_s.include?("/vendor/portable-ruby/")
+  ruby_version = RbConfig::CONFIG["ruby_version"]
+  ruby_path = "#{RbConfig::CONFIG["rubylibprefix"]}/gems/#{ruby_version}"
+
+  $LOAD_PATH.unshift "#{ruby_path}/extensions/#{Gem::Platform.local}/#{ruby_version}-static/debug-1.6.3"
+  $LOAD_PATH.unshift "#{ruby_path}/gems/debug-1.6.3/lib"
+end
+
 unless $LOAD_PATH.include?(HOMEBREW_LIBRARY_PATH.to_s)
   # Insert the path after any existing Homebrew paths (e.g. those inserted by tests and parent processes)
   last_homebrew_path_idx = $LOAD_PATH.rindex do |path|
diff --git a/Library/Homebrew/test/spec_helper.rb b/Library/Homebrew/test/spec_helper.rb
index 1cf4a428ea9c7..b525f7a11bc7e 100644
--- a/Library/Homebrew/test/spec_helper.rb
+++ b/Library/Homebrew/test/spec_helper.rb
@@ -29,7 +29,6 @@
 require "rspec/sorbet"
 require "rubocop/rspec/support"
 require "find"
-require "byebug"
 require "timeout"
 
 $LOAD_PATH.unshift(File.expand_path("#{ENV.fetch("HOMEBREW_LIBRARY")}/Homebrew/test/support/lib"))
@@ -38,6 +37,8 @@
 
 require_relative "../global"
 
+require "debug" if ENV["HOMEBREW_DEBUG"]
+
 require "test/support/quiet_progress_formatter"
 require "test/support/helper/cask"
 require "test/support/helper/files"
@@ -230,14 +231,14 @@
     @__stdin = $stdin.clone
 
     begin
-      if !example.metadata.keys.intersect?([:focus, :byebug]) && !ENV.key?("HOMEBREW_VERBOSE_TESTS")
+      if example.metadata.keys.exclude?(:focus) && !ENV.key?("HOMEBREW_VERBOSE_TESTS")
         $stdout.reopen(File::NULL)
         $stderr.reopen(File::NULL)
+        $stdin.reopen(File::NULL)
       else
-        # don't retry when focusing/debugging
+        # don't retry when focusing
         config.default_retry_count = 0
       end
-      $stdin.reopen(File::NULL)
 
       begin
         timeout = example.metadata.fetch(:timeout, 60)
diff --git a/Library/Homebrew/vendor/bundle/bundler/setup.rb b/Library/Homebrew/vendor/bundle/bundler/setup.rb
index fdcc702b0870c..5a696f1f252c6 100644
--- a/Library/Homebrew/vendor/bundle/bundler/setup.rb
+++ b/Library/Homebrew/vendor/bundle/bundler/setup.rb
@@ -35,8 +35,6 @@ def self.extension_api_version
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/msgpack-1.7.2/lib")
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/extensions/arm64-darwin-20/#{Gem.extension_api_version}/bootsnap-1.18.3")
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/bootsnap-1.18.3/lib")
-$:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/extensions/arm64-darwin-20/#{Gem.extension_api_version}/byebug-11.1.3")
-$:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/byebug-11.1.3/lib")
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/coderay-1.1.3/lib")
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/highline-2.0.3/lib")
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/commander-4.6.0/lib")
diff --git a/completions/bash/brew b/completions/bash/brew
index 318ae832a4d63..289e52bf871e5 100644
--- a/completions/bash/brew
+++ b/completions/bash/brew
@@ -2208,7 +2208,6 @@ _brew_tests() {
   case "${cur}" in
     -*)
       __brewcomp "
-      --byebug
       --changed
       --coverage
       --debug
diff --git a/completions/fish/brew.fish b/completions/fish/brew.fish
index 9167474328f20..ecb629d655642 100644
--- a/completions/fish/brew.fish
+++ b/completions/fish/brew.fish
@@ -1465,10 +1465,9 @@ __fish_brew_complete_arg 'test' -a '(__fish_brew_suggest_formulae_installed)'
 
 
 __fish_brew_complete_cmd 'tests' 'Run Homebrew\'s unit and integration tests'
-__fish_brew_complete_arg 'tests' -l byebug -d 'Enable debugging using byebug'
 __fish_brew_complete_arg 'tests' -l changed -d 'Only runs tests on files that were changed from the master branch'
 __fish_brew_complete_arg 'tests' -l coverage -d 'Generate code coverage reports'
-__fish_brew_complete_arg 'tests' -l debug -d 'Display any debugging information'
+__fish_brew_complete_arg 'tests' -l debug -d 'Enable debugging using ruby/debug, or surface the standard `odebug` output'
 __fish_brew_complete_arg 'tests' -l fail-fast -d 'Exit early on the first failing test'
 __fish_brew_complete_arg 'tests' -l generic -d 'Run only OS-agnostic tests'
 __fish_brew_complete_arg 'tests' -l help -d 'Show this message'
diff --git a/completions/zsh/_brew b/completions/zsh/_brew
index 65e86cf5b5143..e7536ef77e41f 100644
--- a/completions/zsh/_brew
+++ b/completions/zsh/_brew
@@ -1815,10 +1815,9 @@ _brew_test() {
 # brew tests
 _brew_tests() {
   _arguments \
-    '--byebug[Enable debugging using byebug]' \
     '(--only)--changed[Only runs tests on files that were changed from the master branch]' \
     '--coverage[Generate code coverage reports]' \
-    '--debug[Display any debugging information]' \
+    '--debug[Enable debugging using ruby/debug, or surface the standard `odebug` output]' \
     '--fail-fast[Exit early on the first failing test]' \
     '--generic[Run only OS-agnostic tests]' \
     '--help[Show this message]' \
diff --git a/docs/Manpage.md b/docs/Manpage.md
index 498b56171ea23..b4b42f9e8c25e 100644
--- a/docs/Manpage.md
+++ b/docs/Manpage.md
@@ -2650,9 +2650,9 @@ Run Homebrew's unit and integration tests.
 : Include tests that use the GitHub API and tests that use any of the taps for
   official external commands.
 
-`--byebug`
+`--debug`
 
-: Enable debugging using byebug.
+: Enable debugging using ruby/debug, or surface the standard `odebug` output.
 
 `--changed`
 
diff --git a/manpages/brew.1 b/manpages/brew.1
index 270a4f0a6b4dc..2415dca39a57a 100644
--- a/manpages/brew.1
+++ b/manpages/brew.1
@@ -1687,8 +1687,8 @@ Run only OS\-agnostic tests\.
 \fB\-\-online\fP
 Include tests that use the GitHub API and tests that use any of the taps for official external commands\.
 .TP
-\fB\-\-byebug\fP
-Enable debugging using byebug\.
+\fB\-\-debug\fP
+Enable debugging using ruby/debug, or surface the standard \fBodebug\fP output\.
 .TP
 \fB\-\-changed\fP
 Only runs tests on files that were changed from the master branch\.