diff --git a/direct/src/p3d/Packager.py b/direct/src/p3d/Packager.py
index 1f02acffbf..7a3cd5110a 100644
--- a/direct/src/p3d/Packager.py
+++ b/direct/src/p3d/Packager.py
@@ -966,7 +966,15 @@ class Packager:
                     else:
                         # It's just a normal library - find it on the path.
                         filename = Filename.fromOsSpecific(filename)
-                        filename.resolveFilename(path)
+                        if filename.isLocal():
+                            filename.resolveFilename(path)
+                        else:
+                            # It's a fully-specified filename; look
+                            # for it under the system root first.
+                            if self.packager.systemRoot:
+                                f2 = Filename(self.packager.systemRoot + filename.cStr())
+                                if f2.exists():
+                                    filename = f2
 
                     newName = Filename(file.dependencyDir, filename.getBasename())
                     self.addFile(filename, newName = newName.cStr(),
@@ -1754,6 +1762,11 @@ class Packager:
         # This should be set to a Filename.
         self.installDir = None
 
+        # If specified, this is a directory to search first for any
+        # library references, before searching the system.
+        # Particularly useful on OSX to reference the universal SDK.
+        self.systemRoot = None
+
         # The download URL at which these packages will eventually be
         # hosted.
         self.hosts = {}
diff --git a/direct/src/p3d/ppackage.py b/direct/src/p3d/ppackage.py
index 55960c3f28..563e31b3a6 100755
--- a/direct/src/p3d/ppackage.py
+++ b/direct/src/p3d/ppackage.py
@@ -97,6 +97,15 @@ Options:
      platforms, it is probably a mistake to set this.  However, see
      the option -u.
 
+  -R sysroot
+     Specify the sysroot that these files were compiled against.  This
+     will shadow the system shared libraries, so that alternate
+     versions are used instead of the system versions.  If any program
+     references a library, say /usr/lib/libfoo.so, and
+     /sysroot/usr/lib/libfoo.so exists instead, that file will be used
+     instead of the system library.  This is particularly useful for
+     cross-compilation.  At the moment, this is supported only on OSX.
+
   -h
      Display this help
 """
@@ -119,10 +128,11 @@ installSearch = []
 signParams = []
 allowPythonDev = False
 universalBinaries = False
+systemRoot = None
 platforms = []
 
 try:
-    opts, args = getopt.getopt(sys.argv[1:], 'i:ps:S:DuP:h')
+    opts, args = getopt.getopt(sys.argv[1:], 'i:ps:S:DuP:R:h')
 except getopt.error, msg:
     usage(1, msg)
 
@@ -145,6 +155,8 @@ for opt, arg in opts:
         universalBinaries = True
     elif opt == '-P':
         platforms.append(arg)
+    elif opt == '-R':
+        systemRoot = arg
         
     elif opt == '-h':
         usage(0)
@@ -181,6 +193,7 @@ for platform in platforms:
     packager.installSearch = [installDir] + installSearch + packager.installSearch
     packager.signParams = signParams
     packager.allowPythonDev = allowPythonDev
+    packager.systemRoot = systemRoot
 
     try:
         packager.setup()