diff --git a/src/corelib/kernel/qcoreapplication.cpp b/src/corelib/kernel/qcoreapplication.cpp
index 967ed447d5..3d09d858a3 100644
--- a/src/corelib/kernel/qcoreapplication.cpp
+++ b/src/corelib/kernel/qcoreapplication.cpp
@@ -1943,7 +1943,9 @@ QString QCoreApplication::organizationDomain()
     using the empty constructor. This saves having to repeat this
     information each time a QSettings object is created.
 
-    \sa organizationName organizationDomain applicationVersion
+    If not set, the application name defaults to the executable name (since 5.0).
+
+    \sa organizationName organizationDomain applicationVersion applicationFilePath
 */
 void QCoreApplication::setApplicationName(const QString &application)
 {
@@ -1951,6 +1953,15 @@ void QCoreApplication::setApplicationName(const QString &application)
 }
 
 QString QCoreApplication::applicationName()
+{
+    QString appname = coreappdata()->application;
+    if (appname.isEmpty() && QCoreApplication::self)
+        appname = QCoreApplication::self->d_func()->appName();
+    return appname;
+}
+
+// Exported for QDesktopServices (Qt4 behavior compatibility)
+Q_CORE_EXPORT QString qt_applicationName_noFallback()
 {
     return coreappdata()->application;
 }
diff --git a/src/gui/util/qdesktopservices.cpp b/src/gui/util/qdesktopservices.cpp
index 1a6661440c..26aecadcf4 100644
--- a/src/gui/util/qdesktopservices.cpp
+++ b/src/gui/util/qdesktopservices.cpp
@@ -287,17 +287,26 @@ void QDesktopServices::unsetUrlHandler(const QString &scheme)
 
 QString QDesktopServices::storageLocationImpl(StandardLocation type)
 {
-#if defined(Q_OS_UNIX) && !defined(Q_OS_MAC)
     if (type == DataLocation) {
-        QString xdgDataHome = QLatin1String(qgetenv("XDG_DATA_HOME"));
-        if (xdgDataHome.isEmpty())
-            xdgDataHome = QDir::homePath() + QLatin1String("/.local/share");
-        xdgDataHome += QLatin1String("/data/")
-                    + QCoreApplication::organizationName() + QLatin1Char('/')
-                    + QCoreApplication::applicationName();
-        return xdgDataHome;
-    }
+        // Preserve Qt 4 compatibility:
+        // * QCoreApplication::applicationName() must default to empty
+        // * Unix data location is under the "data/" subdirectory
+        extern Q_CORE_EXPORT QString qt_applicationName_noFallback();
+        const QString compatAppName = qt_applicationName_noFallback();
+        const QString baseDir = QStandardPaths::writableLocation(QStandardPaths::GenericDataLocation);
+#if defined(Q_OS_WIN) || defined(Q_OS_MAC)
+        QString result = baseDir;
+        if (!QCoreApplication::organizationName().isEmpty())
+            result += QLatin1Char('/') + QCoreApplication::organizationName();
+        if (!compatAppName.isEmpty())
+            result += QLatin1Char('/') + compatAppName;
+        return result;
+#elif defined(Q_OS_UNIX)
+        return baseDir + QLatin1String("/data/")
+            + QCoreApplication::organizationName() + QLatin1Char('/')
+            + compatAppName;
 #endif
+    }
     return QStandardPaths::writableLocation(static_cast<QStandardPaths::StandardLocation>(type));
 }
 
diff --git a/tests/auto/corelib/io/qstandardpaths/tst_qstandardpaths.cpp b/tests/auto/corelib/io/qstandardpaths/tst_qstandardpaths.cpp
index a6eabbbed6..e9af29494b 100644
--- a/tests/auto/corelib/io/qstandardpaths/tst_qstandardpaths.cpp
+++ b/tests/auto/corelib/io/qstandardpaths/tst_qstandardpaths.cpp
@@ -186,18 +186,12 @@ void tst_qstandardpaths::testDataLocation()
 {
     // On all platforms, DataLocation should be GenericDataLocation / organization name / app name
     // This allows one app to access the data of another app.
-    {
-        const QString base = QStandardPaths::writableLocation(QStandardPaths::GenericDataLocation);
-        const QString app = QStandardPaths::writableLocation(QStandardPaths::DataLocation);
-        QCOMPARE(base, app);
-    }
+    const QString base = QStandardPaths::writableLocation(QStandardPaths::GenericDataLocation);
+    QCOMPARE(QStandardPaths::writableLocation(QStandardPaths::DataLocation), base + "/tst_qstandardpaths");
     QCoreApplication::instance()->setOrganizationName("Qt");
+    QCOMPARE(QStandardPaths::writableLocation(QStandardPaths::DataLocation), base + "/Qt/tst_qstandardpaths");
     QCoreApplication::instance()->setApplicationName("QtTest");
-    {
-        const QString base = QStandardPaths::writableLocation(QStandardPaths::GenericDataLocation);
-        const QString app = QStandardPaths::writableLocation(QStandardPaths::DataLocation);
-        QCOMPARE(app, base + "/Qt/QtTest");
-    }
+    QCOMPARE(QStandardPaths::writableLocation(QStandardPaths::DataLocation), base + "/Qt/QtTest");
 
 #ifdef Q_XDG_PLATFORM
     setDefaultLocations();
diff --git a/tests/auto/corelib/kernel/qcoreapplication/tst_qcoreapplication.cpp b/tests/auto/corelib/kernel/qcoreapplication/tst_qcoreapplication.cpp
index 84d723ca61..f4aefb2726 100644
--- a/tests/auto/corelib/kernel/qcoreapplication/tst_qcoreapplication.cpp
+++ b/tests/auto/corelib/kernel/qcoreapplication/tst_qcoreapplication.cpp
@@ -121,7 +121,8 @@ void tst_QCoreApplication::qAppName()
     int argc = 1;
     char *argv[] = { const_cast<char*>("tst_qcoreapplication") };
     QCoreApplication app(argc, argv);
-    QVERIFY(!::qAppName().isEmpty());
+    QCOMPARE(::qAppName(), QString::fromLatin1("tst_qcoreapplication"));
+    QCOMPARE(QCoreApplication::applicationName(), QString::fromLatin1("tst_qcoreapplication"));
 }
 
 void tst_QCoreApplication::argc()