--- /dev/null
+From 1c75ea0332054c420efd676c147e45eee43e0118 Mon Sep 17 00:00:00 2001
+From: Jonathan Liu <net147@gmail.com>
+Date: Thu, 6 Jun 2013 12:42:13 +1000
+Subject: [PATCH] Don't overwrite QMAKE_QT_CONFIG with empty value
+
+If the mkspec sets QMAKE_QT_CONFIG, QMAKE_QT_CONFIG may be overwritten
+with an empty value from .qmake.cache. Avoid this by first checking
+if the value from .qmake.cache is not empty before assigning it to
+QMAKE_QT_CONFIG.
+
+Upstream-Status: Submitted
+https://codereview.qt-project.org/#change,58109
+
+Change-Id: I95fa630139b8798156a2fb15d0dde630a0a53a0a
+Signed-off-by: Jonathan Liu <net147@gmail.com>
+---
+ mkspecs/features/qt_config.prf | 6 +++++-
+ 1 file changed, 5 insertions(+), 1 deletion(-)
+
+diff --git a/mkspecs/features/qt_config.prf b/mkspecs/features/qt_config.prf
+index fc14cdd..e059b7e 100644
+--- a/mkspecs/features/qt_config.prf
++++ b/mkspecs/features/qt_config.prf
+@@ -1,7 +1,11 @@
+ # This file is loaded by the mkspecs, before .qmake.cache has been loaded.
+ # Consequently, we have to do some stunts to get values out of the cache.
+
+-exists($$_QMAKE_CACHE_):QMAKE_QT_CONFIG = $$fromfile($$_QMAKE_CACHE_, QMAKE_QT_CONFIG)
++exists($$_QMAKE_CACHE_) {
++ qdd = $$fromfile($$_QMAKE_CACHE_, QMAKE_QT_CONFIG)
++ !isEmpty(qdd): QMAKE_QT_CONFIG = $$qdd
++ unset(qdd)
++}
+ isEmpty(QMAKE_QT_CONFIG)|!exists($$QMAKE_QT_CONFIG) {
+ qdd = $$QT_BUILD_TREE
+ isEmpty(qdd):exists($$_QMAKE_CACHE_): qdd = $$fromfile($$_QMAKE_CACHE_, QT_BUILD_TREE)
+--
+1.8.2.3
+