diff --git a/main/src/main/scala/sbt/Defaults.scala b/main/src/main/scala/sbt/Defaults.scala
index d8c072cae..d1db1af98 100755
--- a/main/src/main/scala/sbt/Defaults.scala
+++ b/main/src/main/scala/sbt/Defaults.scala
@@ -1861,7 +1861,7 @@ object Classpaths {
         licenses :== Nil,
         developers :== Nil,
         scmInfo :== None,
-        offline :== false,
+        offline :== java.lang.Boolean.getBoolean("sbt.offline"),
         defaultConfiguration :== Some(Configurations.Compile),
         dependencyOverrides :== Vector.empty,
         libraryDependencies :== Nil,
diff --git a/notes/1.2.0/offline.md b/notes/1.2.0/offline.md
new file mode 100644
index 000000000..6a0a9e68b
--- /dev/null
+++ b/notes/1.2.0/offline.md
@@ -0,0 +1,2 @@
+- `-Dsbt.offline=true` now can set offline mode.
+