diff --git a/activesupport/lib/active_support/core_ext/array/conversions.rb b/activesupport/lib/active_support/core_ext/array/conversions.rb
index 11846f265c45522d35423af4479f8f7a5c84aa31..c53cf3f53060b91154dadc839daac74531b39d65 100644
--- a/activesupport/lib/active_support/core_ext/array/conversions.rb
+++ b/activesupport/lib/active_support/core_ext/array/conversions.rb
@@ -159,6 +159,7 @@ def to_xml(options = {})
     raise "Not all elements respond to to_xml" unless all? { |e| e.respond_to? :to_xml }
     require 'builder' unless defined?(Builder)
 
+    options = options.dup
     options[:root]     ||= all? { |e| e.is_a?(first.class) && first.class.to_s != "Hash" } ? ActiveSupport::Inflector.pluralize(ActiveSupport::Inflector.underscore(first.class.name)) : "records"
     options[:children] ||= options[:root].singularize
     options[:indent]   ||= 2
diff --git a/activesupport/lib/active_support/core_ext/hash/conversions.rb b/activesupport/lib/active_support/core_ext/hash/conversions.rb
index 2a34874d08a953eeb195125e6b1fdf0ca3bd2c02..bd9419e1a28a605e941101a0621325ea757c3259 100644
--- a/activesupport/lib/active_support/core_ext/hash/conversions.rb
+++ b/activesupport/lib/active_support/core_ext/hash/conversions.rb
@@ -86,6 +86,7 @@ def to_query(namespace = nil)
   def to_xml(options = {})
     require 'builder' unless defined?(Builder)
 
+    options = options.dup
     options[:indent] ||= 2
     options.reverse_merge!({ :builder => Builder::XmlMarkup.new(:indent => options[:indent]),
                              :root => "hash" })
diff --git a/activesupport/test/core_ext/array_ext_test.rb b/activesupport/test/core_ext/array_ext_test.rb
index 24d33896ce55bf11f0d34fcc3855b88a8c19d3c0..8198b9bd2c1f182fee3c10101c842b67371458df 100644
--- a/activesupport/test/core_ext/array_ext_test.rb
+++ b/activesupport/test/core_ext/array_ext_test.rb
@@ -302,6 +302,13 @@ def test_to_xml_with_empty
     xml = [].to_xml
     assert_match(/type="array"\/>/, xml)
   end
+
+  def test_to_xml_dups_options
+    options = {:skip_instruct => true}
+    [].to_xml(options)
+    # :builder, etc, shouldn't be added to options
+    assert_equal({:skip_instruct => true}, options)
+  end
 end
 
 class ArrayExtractOptionsTests < Test::Unit::TestCase
diff --git a/activesupport/test/core_ext/hash_ext_test.rb b/activesupport/test/core_ext/hash_ext_test.rb
index ece5466abba088098d0f73c17eb3e93e6055c897..8b0f3fc33c9fc6b43e842164eb07abe01cd9a043 100644
--- a/activesupport/test/core_ext/hash_ext_test.rb
+++ b/activesupport/test/core_ext/hash_ext_test.rb
@@ -880,6 +880,13 @@ def test_datetime_xml_type_with_far_future_date
     assert_equal 30,    alert_at.min
     assert_equal 45,    alert_at.sec
   end
+
+  def test_to_xml_dups_options
+    options = {:skip_instruct => true}
+    {}.to_xml(options)
+    # :builder, etc, shouldn't be added to options
+    assert_equal({:skip_instruct => true}, options)
+  end
 end
 
 class QueryTest < Test::Unit::TestCase