diff --git a/activesupport/lib/active_support/core_ext/string/conversions.rb b/activesupport/lib/active_support/core_ext/string/conversions.rb
index 428fa1f826..d2a2db32bb 100644
--- a/activesupport/lib/active_support/core_ext/string/conversions.rb
+++ b/activesupport/lib/active_support/core_ext/string/conversions.rb
@@ -20,19 +20,17 @@ class String
     return if parts.empty?
 
     now = Time.now
-    offset = parts[:offset]
-    utc_offset = form == :utc ? 0 : now.utc_offset
-    adjustment = offset ? offset - utc_offset : 0
-
-    Time.send(
-      form,
+    time = Time.new(
       parts.fetch(:year, now.year),
       parts.fetch(:mon, now.month),
       parts.fetch(:mday, now.day),
       parts.fetch(:hour, 0),
       parts.fetch(:min, 0),
-      parts.fetch(:sec, 0) + parts.fetch(:sec_fraction, 0)
-    ) - adjustment
+      parts.fetch(:sec, 0) + parts.fetch(:sec_fraction, 0),
+      parts.fetch(:offset, form == :utc ? 0 : nil)
+    )
+
+    form == :utc ? time.utc : time.getlocal
   end
 
   # Converts a string to a Date value.
diff --git a/activesupport/test/core_ext/string_ext_test.rb b/activesupport/test/core_ext/string_ext_test.rb
index 62c5741ffb..8f0ebc13ea 100644
--- a/activesupport/test/core_ext/string_ext_test.rb
+++ b/activesupport/test/core_ext/string_ext_test.rb
@@ -300,9 +300,9 @@ class StringConversionsTest < ActiveSupport::TestCase
       assert_equal Time.local(2005, 2, 27, 23, 50, 19, 275038), "2005-02-27T23:50:19.275038".to_time
       assert_equal Time.utc(2039, 2, 27, 23, 50), "2039-02-27 23:50".to_time(:utc)
       assert_equal Time.local(2039, 2, 27, 23, 50), "2039-02-27 23:50".to_time
-      assert_equal Time.local(2011, 2, 27, 18, 50), "2011-02-27 13:50 -0100".to_time
+      assert_equal Time.local(2011, 2, 27, 17, 50), "2011-02-27 13:50 -0100".to_time
       assert_equal Time.utc(2011, 2, 27, 23, 50), "2011-02-27 22:50 -0100".to_time(:utc)
-      assert_equal Time.local(2005, 2, 27, 23, 50), "2005-02-27 14:50 -0500".to_time
+      assert_equal Time.local(2005, 2, 27, 22, 50), "2005-02-27 14:50 -0500".to_time
       assert_nil "".to_time
     end
   end
@@ -326,6 +326,122 @@ class StringConversionsTest < ActiveSupport::TestCase
     end
   end
 
+  def test_standard_time_string_to_time_when_current_time_is_standard_time
+    with_env_tz "US/Eastern" do
+      Time.stubs(:now).returns(Time.local(2012, 1, 1))
+      assert_equal Time.local(2012, 1, 1, 10, 0), "2012-01-01 10:00".to_time
+      assert_equal Time.utc(2012, 1, 1, 10, 0), "2012-01-01 10:00".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 13, 0), "2012-01-01 10:00 -0800".to_time
+      assert_equal Time.utc(2012, 1, 1, 18, 0), "2012-01-01 10:00 -0800".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 10, 0), "2012-01-01 10:00 -0500".to_time
+      assert_equal Time.utc(2012, 1, 1, 15, 0), "2012-01-01 10:00 -0500".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 5, 0), "2012-01-01 10:00 UTC".to_time
+      assert_equal Time.utc(2012, 1, 1, 10, 0), "2012-01-01 10:00 UTC".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 13, 0), "2012-01-01 10:00 PST".to_time
+      assert_equal Time.utc(2012, 1, 1, 18, 0), "2012-01-01 10:00 PST".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 10, 0), "2012-01-01 10:00 EST".to_time
+      assert_equal Time.utc(2012, 1, 1, 15, 0), "2012-01-01 10:00 EST".to_time(:utc)
+    end
+  end
+
+  def test_standard_time_string_to_time_when_current_time_is_daylight_savings
+    with_env_tz "US/Eastern" do
+      Time.stubs(:now).returns(Time.local(2012, 7, 1))
+      assert_equal Time.local(2012, 1, 1, 10, 0), "2012-01-01 10:00".to_time
+      assert_equal Time.utc(2012, 1, 1, 10, 0), "2012-01-01 10:00".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 13, 0), "2012-01-01 10:00 -0800".to_time
+      assert_equal Time.utc(2012, 1, 1, 18, 0), "2012-01-01 10:00 -0800".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 10, 0), "2012-01-01 10:00 -0500".to_time
+      assert_equal Time.utc(2012, 1, 1, 15, 0), "2012-01-01 10:00 -0500".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 5, 0), "2012-01-01 10:00 UTC".to_time
+      assert_equal Time.utc(2012, 1, 1, 10, 0), "2012-01-01 10:00 UTC".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 13, 0), "2012-01-01 10:00 PST".to_time
+      assert_equal Time.utc(2012, 1, 1, 18, 0), "2012-01-01 10:00 PST".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 10, 0), "2012-01-01 10:00 EST".to_time
+      assert_equal Time.utc(2012, 1, 1, 15, 0), "2012-01-01 10:00 EST".to_time(:utc)
+    end
+  end
+
+  def test_daylight_savings_string_to_time_when_current_time_is_standard_time
+    with_env_tz "US/Eastern" do
+      Time.stubs(:now).returns(Time.local(2012, 1, 1))
+      assert_equal Time.local(2012, 7, 1, 10, 0), "2012-07-01 10:00".to_time
+      assert_equal Time.utc(2012, 7, 1, 10, 0), "2012-07-01 10:00".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 13, 0), "2012-07-01 10:00 -0700".to_time
+      assert_equal Time.utc(2012, 7, 1, 17, 0), "2012-07-01 10:00 -0700".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 10, 0), "2012-07-01 10:00 -0400".to_time
+      assert_equal Time.utc(2012, 7, 1, 14, 0), "2012-07-01 10:00 -0400".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 6, 0), "2012-07-01 10:00 UTC".to_time
+      assert_equal Time.utc(2012, 7, 1, 10, 0), "2012-07-01 10:00 UTC".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 13, 0), "2012-07-01 10:00 PDT".to_time
+      assert_equal Time.utc(2012, 7, 1, 17, 0), "2012-07-01 10:00 PDT".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 10, 0), "2012-07-01 10:00 EDT".to_time
+      assert_equal Time.utc(2012, 7, 1, 14, 0), "2012-07-01 10:00 EDT".to_time(:utc)
+    end
+  end
+
+  def test_daylight_savings_string_to_time_when_current_time_is_daylight_savings
+    with_env_tz "US/Eastern" do
+      Time.stubs(:now).returns(Time.local(2012, 7, 1))
+      assert_equal Time.local(2012, 7, 1, 10, 0), "2012-07-01 10:00".to_time
+      assert_equal Time.utc(2012, 7, 1, 10, 0), "2012-07-01 10:00".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 13, 0), "2012-07-01 10:00 -0700".to_time
+      assert_equal Time.utc(2012, 7, 1, 17, 0), "2012-07-01 10:00 -0700".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 10, 0), "2012-07-01 10:00 -0400".to_time
+      assert_equal Time.utc(2012, 7, 1, 14, 0), "2012-07-01 10:00 -0400".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 6, 0), "2012-07-01 10:00 UTC".to_time
+      assert_equal Time.utc(2012, 7, 1, 10, 0), "2012-07-01 10:00 UTC".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 13, 0), "2012-07-01 10:00 PDT".to_time
+      assert_equal Time.utc(2012, 7, 1, 17, 0), "2012-07-01 10:00 PDT".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 10, 0), "2012-07-01 10:00 EDT".to_time
+      assert_equal Time.utc(2012, 7, 1, 14, 0), "2012-07-01 10:00 EDT".to_time(:utc)
+    end
+  end
+
+  def test_partial_string_to_time_when_current_time_is_standard_time
+    with_env_tz "US/Eastern" do
+      Time.stubs(:now).returns(Time.local(2012, 1, 1))
+      assert_equal Time.local(2012, 1, 1, 10, 0), "10:00".to_time
+      assert_equal Time.utc(2012, 1, 1, 10, 0),  "10:00".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 6, 0), "10:00 -0100".to_time
+      assert_equal Time.utc(2012, 1, 1, 11, 0), "10:00 -0100".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 10, 0), "10:00 -0500".to_time
+      assert_equal Time.utc(2012, 1, 1, 15, 0), "10:00 -0500".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 5, 0), "10:00 UTC".to_time
+      assert_equal Time.utc(2012, 1, 1, 10, 0), "10:00 UTC".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 13, 0), "10:00 PST".to_time
+      assert_equal Time.utc(2012, 1, 1, 18, 0), "10:00 PST".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 12, 0), "10:00 PDT".to_time
+      assert_equal Time.utc(2012, 1, 1, 17, 0), "10:00 PDT".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 10, 0), "10:00 EST".to_time
+      assert_equal Time.utc(2012, 1, 1, 15, 0), "10:00 EST".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 9, 0), "10:00 EDT".to_time
+      assert_equal Time.utc(2012, 1, 1, 14, 0), "10:00 EDT".to_time(:utc)
+    end
+  end
+
+  def test_partial_string_to_time_when_current_time_is_daylight_savings
+    with_env_tz "US/Eastern" do
+      Time.stubs(:now).returns(Time.local(2012, 7, 1))
+      assert_equal Time.local(2012, 7, 1, 10, 0), "10:00".to_time
+      assert_equal Time.utc(2012, 7, 1, 10, 0), "10:00".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 7, 0), "10:00 -0100".to_time
+      assert_equal Time.utc(2012, 7, 1, 11, 0), "10:00 -0100".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 11, 0), "10:00 -0500".to_time
+      assert_equal Time.utc(2012, 7, 1, 15, 0), "10:00 -0500".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 6, 0), "10:00 UTC".to_time
+      assert_equal Time.utc(2012, 7, 1, 10, 0), "10:00 UTC".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 14, 0), "10:00 PST".to_time
+      assert_equal Time.utc(2012, 7, 1, 18, 0), "10:00 PST".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 13, 0), "10:00 PDT".to_time
+      assert_equal Time.utc(2012, 7, 1, 17, 0), "10:00 PDT".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 11, 0), "10:00 EST".to_time
+      assert_equal Time.utc(2012, 7, 1, 15, 0), "10:00 EST".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 10, 0), "10:00 EDT".to_time
+      assert_equal Time.utc(2012, 7, 1, 14, 0), "10:00 EDT".to_time(:utc)
+    end
+  end
+
   def test_string_to_datetime
     assert_equal DateTime.civil(2039, 2, 27, 23, 50), "2039-02-27 23:50".to_datetime
     assert_equal 0, "2039-02-27 23:50".to_datetime.offset # use UTC offset