diff --git a/builder/kojid b/builder/kojid
index eb2fa4c9..686461a2 100755
--- a/builder/kojid
+++ b/builder/kojid
@@ -1917,10 +1917,23 @@ class BuildArchTask(BaseTaskHandler):
     Methods = ['buildArch']
 
     def weight(self):
-        # XXX - this one needs to figure the weight from the package to be
-        # built
         return 1.5
 
+    def updateWeight(self, name):
+        """
+        Update the weight of this task based on the package we're building.
+        weight is scaled from a minimum of 1.5 to a maximum of 6, based on
+        the average duration of a build of this package.
+        """
+        avg = session.getAverageBuildDuration(name)
+        if not avg:
+            return
+        # increase the task weight by 0.75 for every hour of build duration
+        adj = (avg / 4800.0)
+        # cap the adjustment at +4.5
+        weight = self.weight() + min(4.5, adj)
+        session.host.setTaskWeight(self.id, weight)
+
     def srpm_sanity_checks(self, filename):
         header = koji.get_rpm_header(filename)
 
@@ -1962,6 +1975,8 @@ class BuildArchTask(BaseTaskHandler):
         # if not h[rpm.RPMTAG_DISTRIBUTION]:
         #    raise koji.BuildError, "the distribution tag is not set in the original srpm"
 
+        self.updateWeight(name)
+
         rootopts = {
             'repo_id': repo_id
             }
diff --git a/hub/kojihub.py b/hub/kojihub.py
index 16d1686a..a201fcfd 100644
--- a/hub/kojihub.py
+++ b/hub/kojihub.py
@@ -5366,11 +5366,14 @@ class RootExports(object):
             tag = get_tag_id(tag,strict=True)
         return readTaggedRPMS(tag, package=package, arch=arch, event=event,inherit=True,latest=True, rpmsigs=rpmsigs)
 
-    def getAverageBuildDuration(self, packageID):
-        """Get the average duration of a build of a package with
-        the given ID.  Returns a floating-point value indicating the
+    def getAverageBuildDuration(self, package):
+        """Get the average duration of a build of the given package.
+        Returns a floating-point value indicating the
         average number of seconds the package took to build.  If the package
         has never been built, return None."""
+        packageID = get_package_id(package)
+        if not packageID:
+            return None
         st_complete = koji.BUILD_STATES['COMPLETE']
         query = """SELECT EXTRACT(epoch FROM avg(build.completion_time - events.time))
                      FROM build