Index: pym/_emerge/depgraph.py
===================================================================
--- pym/_emerge/depgraph.py	(revision 13801)
+++ pym/_emerge/depgraph.py	(working copy)
@@ -572,7 +572,8 @@
 		orig_use, orig_iuse, cur_use, cur_iuse):
 		"""Return a set of flags that trigger reinstallation, or None if there
 		are no such flags."""
-		if "--newuse" in self._frozen_config.myopts:
+		if "--newuse" in self._frozen_config.myopts or \
+			self._frozen_config.myopts["--binpkg-respect-use"]:
 			flags = set(orig_iuse.symmetric_difference(
 				cur_iuse).difference(forced_flags))
 			flags.update(orig_iuse.intersection(orig_use).symmetric_difference(
@@ -2155,7 +2156,8 @@
 					# reject the built package if necessary.
 					if built and not installed and \
 						("--newuse" in self._frozen_config.myopts or \
-						"--reinstall" in self._frozen_config.myopts):
+						"--reinstall" in self._frozen_config.myopts or \
+						self._frozen_config.myopts["--binpkg-respect-use"]):
 						iuses = pkg.iuse.all
 						old_use = pkg.use.enabled
 						if myeb:
Index: pym/_emerge/main.py
===================================================================
--- pym/_emerge/main.py	(revision 13801)
+++ pym/_emerge/main.py	(working copy)
@@ -368,6 +368,7 @@
 	jobs_opts = ("-j", "--jobs")
 	default_arg_opts = {
 		'--deselect'   : ('n',),
+		'--binpkg-respect-use'   : ('n',),
 		'--root-deps'  : ('rdeps',),
 	}
 	arg_stack = args[:]
@@ -486,6 +487,14 @@
 			"type":"choice",
 			"choices":["changed-use"]
 		},
+
+		"--binpkg-respect-use": {
+			"help"    : "discard binary packages if theier use flags \
+				don't match the current configuration",
+			"type"    : "choice",
+			"choices" : ("y", "n")
+		},
+
 		"--root": {
 		 "help"   : "specify the target root filesystem for merging packages",
 		 "action" : "store"
@@ -527,6 +536,11 @@
 	if myoptions.deselect == "True":
 		myoptions.deselect = True
 
+	if myoptions.binpkg_respect_use == "y":
+		myoptions.binpkg_respect_use = True
+	else:
+		myoptions.binpkg_respect_use = False
+
 	if myoptions.root_deps == "True":
 		myoptions.root_deps = True
 
Index: man/emerge.1
===================================================================
--- man/emerge.1	(revision 13801)
+++ man/emerge.1	(working copy)
@@ -249,6 +249,10 @@
 buffer is not cleared prior to the prompt, so an accidental press of the
 "Enter" key at any time prior to the prompt will be interpreted as a choice!\fR
 .TP
+.BR "\-\-binpkg\-respect\-use < y | n >"
+Tells emerge to ignore binary packages if their use flags don't match the
+current configuration. (default: \'n\')
+.TP
 .BR "\-\-buildpkg " (\fB\-b\fR)
 Tells emerge to build binary packages for all ebuilds processed in
 addition to actually merging the packages.  Useful for maintainers