diff --git a/lib/rubygems/commands/build_command.rb b/lib/rubygems/commands/build_command.rb
index 2ec83241418d13..cfe1f8ec3c86f4 100644
--- a/lib/rubygems/commands/build_command.rb
+++ b/lib/rubygems/commands/build_command.rb
@@ -25,13 +25,6 @@ def initialize
     add_option "-o", "--output FILE", "output gem with the given filename" do |value, options|
       options[:output] = value
     end
-
-    add_option "-C PATH", "Run as if gem build was started in <PATH> instead of the current working directory." do |value, options|
-      options[:build_path] = value
-    end
-    deprecate_option "-C",
-                     version: "4.0",
-                     extra_msg: "-C is a global flag now. Use `gem -C PATH build GEMSPEC_FILE [options]` instead"
   end
 
   def arguments # :nodoc:
diff --git a/lib/rubygems/dependency_installer.rb b/lib/rubygems/dependency_installer.rb
index de86d9bf7e9be0..a6cfc3c07af76d 100644
--- a/lib/rubygems/dependency_installer.rb
+++ b/lib/rubygems/dependency_installer.rb
@@ -7,14 +7,12 @@
 require_relative "spec_fetcher"
 require_relative "user_interaction"
 require_relative "available_set"
-require_relative "deprecate"
 
 ##
 # Installs a gem along with all its dependencies from local and remote gems.
 
 class Gem::DependencyInstaller
   include Gem::UserInteraction
-  extend Gem::Deprecate
 
   DEFAULT_OPTIONS = { # :nodoc:
     env_shebang: false,
diff --git a/lib/rubygems/dependency_list.rb b/lib/rubygems/dependency_list.rb
index 99643a426d423a..d50cfe2d547b6d 100644
--- a/lib/rubygems/dependency_list.rb
+++ b/lib/rubygems/dependency_list.rb
@@ -7,7 +7,6 @@
 #++
 
 require_relative "vendored_tsort"
-require_relative "deprecate"
 
 ##
 # Gem::DependencyList is used for installing and uninstalling gems in the
diff --git a/lib/rubygems/exceptions.rb b/lib/rubygems/exceptions.rb
index 0f65c76daf5af8..40485bbadff81a 100644
--- a/lib/rubygems/exceptions.rb
+++ b/lib/rubygems/exceptions.rb
@@ -1,6 +1,5 @@
 # frozen_string_literal: true
 
-require_relative "deprecate"
 require_relative "unknown_command_spell_checker"
 
 ##
diff --git a/lib/rubygems/gem_runner.rb b/lib/rubygems/gem_runner.rb
index 4cb924677f8360..e60cebd0cbb120 100644
--- a/lib/rubygems/gem_runner.rb
+++ b/lib/rubygems/gem_runner.rb
@@ -8,7 +8,6 @@
 
 require_relative "../rubygems"
 require_relative "command_manager"
-require_relative "deprecate"
 
 ##
 # Run an instance of the gem program.
diff --git a/lib/rubygems/user_interaction.rb b/lib/rubygems/user_interaction.rb
index 571137629406fb..9fe3e755c48f63 100644
--- a/lib/rubygems/user_interaction.rb
+++ b/lib/rubygems/user_interaction.rb
@@ -6,7 +6,6 @@
 # See LICENSE.txt for permissions.
 #++
 
-require_relative "deprecate"
 require_relative "text"
 
 ##
@@ -170,8 +169,6 @@ def verbose(msg = nil)
 # Gem::StreamUI implements a simple stream based user interface.
 
 class Gem::StreamUI
-  extend Gem::Deprecate
-
   ##
   # The input stream
 
diff --git a/test/rubygems/test_gem_commands_build_command.rb b/test/rubygems/test_gem_commands_build_command.rb
index d44126d2046a94..9339f41f7cb875 100644
--- a/test/rubygems/test_gem_commands_build_command.rb
+++ b/test/rubygems/test_gem_commands_build_command.rb
@@ -43,16 +43,6 @@ def test_handle_options
     assert_includes Gem.platforms, Gem::Platform.local
   end
 
-  def test_handle_deprecated_options
-    use_ui @ui do
-      @cmd.handle_options %w[-C ./test/dir]
-    end
-
-    assert_equal "WARNING:  The \"-C\" option has been deprecated and will be removed in Rubygems 4.0. " \
-                 "-C is a global flag now. Use `gem -C PATH build GEMSPEC_FILE [options]` instead\n",
-                 @ui.error
-  end
-
   def test_options_filename
     gemspec_file = File.join(@tempdir, @gem.spec_name)
 
diff --git a/test/rubygems/test_gem_commands_help_command.rb b/test/rubygems/test_gem_commands_help_command.rb
index 01ab4aab2fe46d..4ce7285d1f8ce2 100644
--- a/test/rubygems/test_gem_commands_help_command.rb
+++ b/test/rubygems/test_gem_commands_help_command.rb
@@ -36,7 +36,7 @@ def test_gem_help_platforms
 
   def test_gem_help_build
     util_gem "build" do |out, err|
-      assert_match(/-C PATH *Run as if gem build was started in <PATH>/, out)
+      assert_match(/--platform PLATFORM\s+Specify the platform of gem to build/, out)
       assert_equal "", err
     end
   end