diff --git a/main/src/main/scala/sbt/Defaults.scala b/main/src/main/scala/sbt/Defaults.scala
index e75c97832..cd05b9c77 100755
--- a/main/src/main/scala/sbt/Defaults.scala
+++ b/main/src/main/scala/sbt/Defaults.scala
@@ -3,7 +3,7 @@
  */
 package sbt
 
-import scala.concurrent.duration.Duration
+import scala.concurrent.duration.{ FiniteDuration, Duration }
 import Attributed.data
 import Scope.{ fillTaskAxis, GlobalScope, ThisScope }
 import sbt.Compiler.InputsWithPrevious
@@ -27,7 +27,7 @@ import org.apache.ivy.core.module.{ descriptor, id }
 import descriptor.ModuleDescriptor, id.ModuleRevisionId
 import java.io.{ File, PrintWriter }
 import java.net.{ URI, URL, MalformedURLException }
-import java.util.concurrent.Callable
+import java.util.concurrent.{ TimeUnit, Callable }
 import sbinary.DefaultProtocol.StringFormat
 import Cache.seqFormat
 import CommandStrings.ExportStream
@@ -115,7 +115,8 @@ object Defaults extends BuildCommon {
       pomPostProcess :== idFun,
       pomAllRepositories :== false,
       pomIncludeRepository :== Classpaths.defaultRepositoryFilter,
-      updateOptions := UpdateOptions()
+      updateOptions := UpdateOptions(),
+      forceUpdatePeriod :== None
     )
 
   /** Core non-plugin settings for sbt builds.  These *must* be on every build or the sbt engine will fail to run at all. */
@@ -1324,7 +1325,15 @@ object Classpaths {
   def updateTask: Initialize[Task[UpdateReport]] = Def.task {
     val depsUpdated = transitiveUpdate.value.exists(!_.stats.cached)
     val isRoot = executionRoots.value contains resolvedScoped.value
+    val forceUpdate = forceUpdatePeriod.value
     val s = streams.value
+    val fullUpdateOutput = s.cacheDirectory / "out"
+    val forceUpdateByTime = forceUpdate match {
+      case None => false
+      case Some(period) =>
+        val elapsedDuration = new FiniteDuration(System.currentTimeMillis() - fullUpdateOutput.lastModified(), TimeUnit.MILLISECONDS)
+        fullUpdateOutput.exists() && elapsedDuration > period
+    }
     val scalaProvider = appConfiguration.value.provider.scalaProvider
 
     // Only substitute unmanaged jars for managed jars when the major.minor parts of the versions the same for:
@@ -1360,7 +1369,7 @@ object Classpaths {
       if (executionRoots.value exists { _.key == evicted.key }) EvictionWarningOptions.empty
       else (evictionWarningOptions in update).value
     cachedUpdate(s.cacheDirectory / updateCacheName.value, show, ivyModule.value, uc, transform,
-      skip = (skip in update).value, force = isRoot, depsUpdated = depsUpdated,
+      skip = (skip in update).value, force = isRoot || forceUpdateByTime, depsUpdated = depsUpdated,
       uwConfig = uwConfig, logicalClock = logicalClock, depDir = Some(depDir),
       ewo = ewo, log = s.log)
   }
diff --git a/main/src/main/scala/sbt/Keys.scala b/main/src/main/scala/sbt/Keys.scala
index 59faafdae..939dd9b77 100644
--- a/main/src/main/scala/sbt/Keys.scala
+++ b/main/src/main/scala/sbt/Keys.scala
@@ -5,7 +5,7 @@ package sbt
 
 import java.io.File
 import java.net.URL
-import scala.concurrent.duration.Duration
+import scala.concurrent.duration.{ FiniteDuration, Duration }
 import Def.ScopedKey
 import complete._
 import inc.Analysis
@@ -324,6 +324,7 @@ object Keys {
   val publishArtifact = SettingKey[Boolean]("publish-artifact", "Enables (true) or disables (false) publishing an artifact.", AMinusSetting)
   val packagedArtifact = TaskKey[(Artifact, File)]("packaged-artifact", "Generates a packaged artifact, returning the Artifact and the produced File.", CTask)
   val checksums = SettingKey[Seq[String]]("checksums", "The list of checksums to generate and to verify for dependencies.", BSetting)
+  val forceUpdatePeriod = SettingKey[Option[FiniteDuration]]("force-update-period", "Duration after which to force a full update to occur", CSetting)
 
   val classifiersModule = TaskKey[GetClassifiersModule]("classifiers-module", rank = CTask)
   val conflictWarning = SettingKey[ConflictWarning]("conflict-warning", "Configures warnings for conflicts in dependency management.", CSetting)
diff --git a/notes/0.13.9/forceupdateperiod.markdown b/notes/0.13.9/forceupdateperiod.markdown
new file mode 100644
index 000000000..49e171b5d
--- /dev/null
+++ b/notes/0.13.9/forceupdateperiod.markdown
@@ -0,0 +1,9 @@
+  [@ajsquared]: https://github.com/ajsquared
+
+
+### Changes with compatibility implications
+
+### Improvements
+- Adds `forceUpdatePeriod` key, that takes values of `Option[FiniteDuration]`.  If set, a full `update` will occur after that amount of time without needing to explicitly run the `update` task. By [@ajsquared][@ajsquared]
+
+### Fixes
diff --git a/sbt/src/sbt-test/dependency-management/force-update-period/build.sbt b/sbt/src/sbt-test/dependency-management/force-update-period/build.sbt
new file mode 100644
index 000000000..ca910bdd9
--- /dev/null
+++ b/sbt/src/sbt-test/dependency-management/force-update-period/build.sbt
@@ -0,0 +1,13 @@
+libraryDependencies += "log4j" % "log4j" % "1.2.16" % "compile"
+
+autoScalaLibrary := false
+
+TaskKey[Unit]("check-last-update-time") <<= streams map { (s) =>
+  val fullUpdateOutput = s.cacheDirectory / "out"
+  val timeDiff = System.currentTimeMillis()-fullUpdateOutput.lastModified()
+  val exists = fullUpdateOutput.exists()
+  s.log.info(s"Amount of time since last full update: $timeDiff")
+  if (exists && timeDiff > 5000) {
+    sys.error("Full update not perfomed")
+  }
+}
\ No newline at end of file
diff --git a/sbt/src/sbt-test/dependency-management/force-update-period/test b/sbt/src/sbt-test/dependency-management/force-update-period/test
new file mode 100644
index 000000000..39e776d09
--- /dev/null
+++ b/sbt/src/sbt-test/dependency-management/force-update-period/test
@@ -0,0 +1,11 @@
+$ absent target/resolution-cache
+> compile
+$ exists target/resolution-cache
+> checkLastUpdateTime
+$ sleep 10000
+> compile
+# This is expected to fail
+-> checkLastUpdateTime
+> set forceUpdatePeriod := Some(new scala.concurrent.duration.FiniteDuration(5000, java.util.concurrent.TimeUnit.MILLISECONDS))
+> compile
+> checkLastUpdateTime
\ No newline at end of file