diff --git a/lib/bundled_gems.rb b/lib/bundled_gems.rb
new file mode 100644
index 00000000000000..82f35a745e209b
--- /dev/null
+++ b/lib/bundled_gems.rb
@@ -0,0 +1,23 @@
+module Gem
+  BUNDLED_GEMS = {
+    "rexml" => "3.0.0",
+    "rss" => "3.0.0",
+    "webrick" => "3.0.0",
+    "matrix" => "3.1.0",
+    "net-ftp" => "3.1.0",
+    "net-imap" => "3.1.0",
+    "net-pop" => "3.1.0",
+    "net-smtp" => "3.1.0",
+    "abbrev" => "3.4.0",
+    "observer" => "3.4.0",
+    "getoptlong" => "3.4.0",
+    "resolv-replace" => "3.4.0",
+    "rinda" => "3.4.0",
+    "nkf" => "3.4.0",
+    "syslog" => "3.4.0",
+    "drb" => "3.4.0",
+    "mutex_m" => "3.4.0",
+    "csv" => "3.4.0",
+    "base64" => "3.4.0"
+  }.freeze
+end
diff --git a/lib/bundler/rubygems_ext.rb b/lib/bundler/rubygems_ext.rb
index 1520deaf316a87..b96edd5e2d81f5 100644
--- a/lib/bundler/rubygems_ext.rb
+++ b/lib/bundler/rubygems_ext.rb
@@ -29,29 +29,6 @@
 end
 
 module Gem
-
-  BUNDLED_GEMS = {
-    "rexml" => "3.0.0",
-    "rss" => "3.0.0",
-    "webrick" => "3.0.0",
-    "matrix" => "3.1.0",
-    "net-ftp" => "3.1.0",
-    "net-imap" => "3.1.0",
-    "net-pop" => "3.1.0",
-    "net-smtp" => "3.1.0",
-    "abbrev" => "3.4.0",
-    "observer" => "3.4.0",
-    "getoptlong" => "3.4.0",
-    "resolv-replace" => "3.4.0",
-    "rinda" => "3.4.0",
-    "nkf" => "3.4.0",
-    "syslog" => "3.4.0",
-    "drb" => "3.4.0",
-    "mutex_m" => "3.4.0",
-    "csv" => "3.4.0",
-    "base64" => "3.4.0"
-  }.freeze
-
   class Specification
     include ::Bundler::MatchMetadata
     include ::Bundler::MatchPlatform
diff --git a/lib/bundler/rubygems_integration.rb b/lib/bundler/rubygems_integration.rb
index 8f2b6994edaf6d..0b82729a48989d 100644
--- a/lib/bundler/rubygems_integration.rb
+++ b/lib/bundler/rubygems_integration.rb
@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require "rubygems" unless defined?(Gem)
+require "bundled_gems" unless defined?(Gem::BUNDLED_GEMS)
 
 module Bundler
   class RubygemsIntegration
@@ -225,6 +226,20 @@ def security_policies
       end
     end
 
+    def reverse_rubygems_kernel_mixin
+      # Disable rubygems' gem activation system
+      if Gem.respond_to?(:discover_gems_on_require=)
+        Gem.discover_gems_on_require = false
+      else
+        kernel = (class << ::Kernel; self; end)
+        [kernel, ::Kernel].each do |k|
+          if k.private_method_defined?(:gem_original_require)
+            redefine_method(k, :require, k.instance_method(:gem_original_require))
+          end
+        end
+      end
+    end
+
     def replace_require(specs)
       return if [::Kernel.singleton_class, ::Kernel].any?{|klass| klass.respond_to?(:no_warning_require)}
 
@@ -370,7 +385,11 @@ def replace_bin_path(specs_by_name)
     def replace_entrypoints(specs)
       specs_by_name = add_default_gems_to(specs)
 
-      replace_require(specs)
+      if defined?(::Gem::BUNDLED_GEMS)
+        replace_require(specs)
+      else
+        reverse_rubygems_kernel_mixin
+      end
       replace_gem(specs, specs_by_name)
       stub_rubygems(specs)
       replace_bin_path(specs_by_name)
diff --git a/spec/bundler/runtime/setup_spec.rb b/spec/bundler/runtime/setup_spec.rb
index 88ec1bcdc95a3a..0cafd4505cccb5 100644
--- a/spec/bundler/runtime/setup_spec.rb
+++ b/spec/bundler/runtime/setup_spec.rb
@@ -1556,7 +1556,12 @@ def require(path)
       gem "rack"
     G
 
+
     ruby <<-R
+      module Gem
+        remove_const :BUNDLED_GEMS if defined?(BUNDLED_GEMS)
+        BUNDLED_GEMS = { "csv" => "1.0.0" }
+      end
       require 'bundler/setup'
       require 'csv'
     R
@@ -1575,6 +1580,10 @@ def require(path)
     G
 
     ruby <<-R
+      module Gem
+        remove_const :BUNDLED_GEMS if defined?(BUNDLED_GEMS)
+        BUNDLED_GEMS = { "csv" => "1.0.0" }
+      end
       require 'csv'
       require 'bundler/setup'
       require 'csv'
@@ -1594,6 +1603,10 @@ def require(path)
     G
 
     ruby <<-R
+      module Gem
+        remove_const :BUNDLED_GEMS if defined?(BUNDLED_GEMS)
+        BUNDLED_GEMS = { "csv" => "1.0.0" }
+      end
       require 'bundler/setup'
       require 'csv'
     R
@@ -1615,6 +1628,10 @@ def require(path)
     G
 
     ruby <<-R
+      module Gem
+        remove_const :BUNDLED_GEMS if defined?(BUNDLED_GEMS)
+        BUNDLED_GEMS = { "csv" => "1.0.0", "net-imap" => "0.0.1" }
+      end
       require 'bundler/setup'
       begin
         require 'net/imap'