diff --git a/src/plugins/qt4projectmanager/qt4nodes.cpp b/src/plugins/qt4projectmanager/qt4nodes.cpp
index 2553c1f25d7..26568c4dd61 100644
--- a/src/plugins/qt4projectmanager/qt4nodes.cpp
+++ b/src/plugins/qt4projectmanager/qt4nodes.cpp
@@ -56,6 +56,7 @@
 #include <utils/hostosinfo.h>
 #include <utils/stringutils.h>
 #include <proparser/prowriter.h>
+#include <proparser/qmakevfs.h>
 #include <algorithm>
 
 #include <QDebug>
@@ -1135,8 +1136,9 @@ void Qt4PriFileNode::changeFiles(const FileType fileType,
             lines = contents.split(QLatin1Char('\n'));
         }
 
+        QMakeVfs vfs;
         QtSupport::ProMessageHandler handler;
-        QMakeParser parser(0, &handler);
+        QMakeParser parser(0, &vfs, &handler);
         includeFile = parser.parsedProBlock(contents, m_projectFilePath, 1);
     }
 
diff --git a/src/plugins/qt4projectmanager/qt4project.cpp b/src/plugins/qt4projectmanager/qt4project.cpp
index b2efd28323c..aa811840313 100644
--- a/src/plugins/qt4projectmanager/qt4project.cpp
+++ b/src/plugins/qt4projectmanager/qt4project.cpp
@@ -46,6 +46,7 @@
 #include <coreplugin/documentmanager.h>
 #include <cpptools/cppmodelmanagerinterface.h>
 #include <qmljstools/qmljsmodelmanager.h>
+#include <projectexplorer/buildmanager.h>
 #include <projectexplorer/buildtargetinfo.h>
 #include <projectexplorer/deploymentdata.h>
 #include <projectexplorer/toolchain.h>
@@ -53,6 +54,7 @@
 #include <projectexplorer/target.h>
 #include <projectexplorer/projectexplorer.h>
 #include <projectexplorer/projectmacroexpander.h>
+#include <proparser/qmakevfs.h>
 #include <qtsupport/profilereader.h>
 #include <qtsupport/qtkitinformation.h>
 
@@ -344,6 +346,7 @@ Qt4Project::Qt4Project(Qt4Manager *manager, const QString& fileName) :
     m_nodesWatcher(new Internal::Qt4NodesWatcher(this)),
     m_fileInfo(new Qt4ProjectFile(fileName, this)),
     m_projectFiles(new Qt4ProjectFiles),
+    m_qmakeVfs(new QMakeVfs),
     m_qmakeGlobals(0),
     m_asyncUpdateFutureInterface(0),
     m_pendingEvaluateFuturesCount(0),
@@ -358,6 +361,10 @@ Qt4Project::Qt4Project(Qt4Manager *manager, const QString& fileName) :
     m_asyncUpdateTimer.setSingleShot(true);
     m_asyncUpdateTimer.setInterval(3000);
     connect(&m_asyncUpdateTimer, SIGNAL(timeout()), this, SLOT(asyncUpdate()));
+
+    connect(ProjectExplorerPlugin::instance()->buildManager(),
+            SIGNAL(buildQueueFinished(bool)),
+            SLOT(buildFinished(bool)));
 }
 
 Qt4Project::~Qt4Project()
@@ -365,6 +372,7 @@ Qt4Project::~Qt4Project()
     m_codeModelFuture.cancel();
     m_asyncUpdateState = ShuttingDown;
     m_manager->unregisterProject(this);
+    delete m_qmakeVfs;
     delete m_projectFiles;
     m_cancelEvaluate = true;
     // Deleting the root node triggers a few things, make sure rootProjectNode
@@ -847,6 +855,9 @@ void Qt4Project::asyncUpdate()
 {
     if (debug)
         qDebug()<<"async update, timer expired, doing now";
+
+    m_qmakeVfs->invalidateCache();
+
     Q_ASSERT(!m_asyncUpdateFutureInterface);
     m_asyncUpdateFutureInterface = new QFutureInterface<void>();
 
@@ -877,6 +888,12 @@ void Qt4Project::asyncUpdate()
     m_asyncUpdateState = AsyncUpdateInProgress;
 }
 
+void Qt4Project::buildFinished(bool success)
+{
+    if (success)
+        m_qmakeVfs->invalidateContents();
+}
+
 ProjectExplorer::IProjectManager *Qt4Project::projectManager() const
 {
     return m_manager;
@@ -1002,7 +1019,7 @@ QtSupport::ProFileReader *Qt4Project::createProFileReader(const Qt4ProFileNode *
     }
     ++m_qmakeGlobalsRefCnt;
 
-    QtSupport::ProFileReader *reader = new QtSupport::ProFileReader(m_qmakeGlobals);
+    QtSupport::ProFileReader *reader = new QtSupport::ProFileReader(m_qmakeGlobals, m_qmakeVfs);
 
     reader->setOutputDir(qt4ProFileNode->buildDir());
 
diff --git a/src/plugins/qt4projectmanager/qt4project.h b/src/plugins/qt4projectmanager/qt4project.h
index 2f402081536..a4bb93b1b3c 100644
--- a/src/plugins/qt4projectmanager/qt4project.h
+++ b/src/plugins/qt4projectmanager/qt4project.h
@@ -42,6 +42,7 @@
 
 QT_BEGIN_NAMESPACE
 class ProFileGlobals;
+class QMakeVfs;
 QT_END_NAMESPACE
 
 namespace ProjectExplorer { class DeploymentData; }
@@ -158,6 +159,7 @@ protected:
 
 private slots:
     void asyncUpdate();
+    void buildFinished(bool success);
 
     void activeTargetWasChanged();
 
@@ -198,6 +200,8 @@ private:
     // cached lists of all of files
     Internal::Qt4ProjectFiles *m_projectFiles;
 
+    QMakeVfs *m_qmakeVfs;
+
     // cached data during project rescan
     ProFileGlobals *m_qmakeGlobals;
     int m_qmakeGlobalsRefCnt;
diff --git a/src/plugins/qtsupport/baseqtversion.cpp b/src/plugins/qtsupport/baseqtversion.cpp
index 093123caa8b..fcb447bf827 100644
--- a/src/plugins/qtsupport/baseqtversion.cpp
+++ b/src/plugins/qtsupport/baseqtversion.cpp
@@ -36,6 +36,7 @@
 
 #include "qtversionmanager.h"
 #include "profilereader.h"
+#include <proparser/qmakevfs.h>
 #include <projectexplorer/toolchainmanager.h>
 #include <projectexplorer/toolchain.h>
 #include <projectexplorer/projectexplorer.h>
@@ -780,12 +781,13 @@ void BaseQtVersion::ensureMkSpecParsed() const
     if (mkspecPath().isEmpty())
         return;
 
+    QMakeVfs vfs;
     ProFileGlobals option;
     option.setProperties(versionInfo());
     ProMessageHandler msgHandler(true);
     ProFileCacheManager::instance()->incRefCount();
-    QMakeParser parser(ProFileCacheManager::instance()->cache(), &msgHandler);
-    ProFileEvaluator evaluator(&option, &parser, &msgHandler);
+    QMakeParser parser(ProFileCacheManager::instance()->cache(), &vfs, &msgHandler);
+    ProFileEvaluator evaluator(&option, &parser, &vfs, &msgHandler);
     evaluator.loadNamedSpec(mkspecPath().toString(), false);
 
     parseMkSpec(&evaluator);
diff --git a/src/plugins/qtsupport/profilereader.cpp b/src/plugins/qtsupport/profilereader.cpp
index b538c0e6cc3..747c4f14ff5 100644
--- a/src/plugins/qtsupport/profilereader.cpp
+++ b/src/plugins/qtsupport/profilereader.cpp
@@ -65,9 +65,9 @@ void ProMessageHandler::fileMessage(const QString &)
 }
 
 
-ProFileReader::ProFileReader(ProFileGlobals *option)
-    : QMakeParser(ProFileCacheManager::instance()->cache(), this)
-    , ProFileEvaluator(option, this, this)
+ProFileReader::ProFileReader(ProFileGlobals *option, QMakeVfs *vfs)
+    : QMakeParser(ProFileCacheManager::instance()->cache(), vfs, this)
+    , ProFileEvaluator(option, this, vfs, this)
     , m_ignoreLevel(0)
 {
 }
diff --git a/src/plugins/qtsupport/profilereader.h b/src/plugins/qtsupport/profilereader.h
index 2ba4c99aa67..3bd8a914b8c 100644
--- a/src/plugins/qtsupport/profilereader.h
+++ b/src/plugins/qtsupport/profilereader.h
@@ -69,7 +69,7 @@ class QTSUPPORT_EXPORT ProFileReader : public ProMessageHandler, public QMakePar
     Q_OBJECT
 
 public:
-    ProFileReader(ProFileGlobals *option);
+    ProFileReader(ProFileGlobals *option, QMakeVfs *vfs);
     ~ProFileReader();
 
     QList<ProFile*> includeFiles() const;
diff --git a/src/plugins/qtsupport/qtversionfactory.cpp b/src/plugins/qtsupport/qtversionfactory.cpp
index 7ff99b6ff4f..cac661f629e 100644
--- a/src/plugins/qtsupport/qtversionfactory.cpp
+++ b/src/plugins/qtsupport/qtversionfactory.cpp
@@ -31,6 +31,8 @@
 #include "profilereader.h"
 #include "baseqtversion.h"
 
+#include <proparser/qmakevfs.h>
+
 #include <extensionsystem/pluginmanager.h>
 #include <utils/environment.h>
 
@@ -61,12 +63,13 @@ BaseQtVersion *QtVersionFactory::createQtVersionFromQMakePath(const Utils::FileN
         return 0;
     Utils::FileName mkspec = BaseQtVersion::mkspecFromVersionInfo(versionInfo);
 
+    QMakeVfs vfs;
     ProFileGlobals globals;
     globals.setProperties(versionInfo);
     ProMessageHandler msgHandler(true);
     ProFileCacheManager::instance()->incRefCount();
-    QMakeParser parser(ProFileCacheManager::instance()->cache(), &msgHandler);
-    ProFileEvaluator evaluator(&globals, &parser, &msgHandler);
+    QMakeParser parser(ProFileCacheManager::instance()->cache(), &vfs, &msgHandler);
+    ProFileEvaluator evaluator(&globals, &parser, &vfs, &msgHandler);
     evaluator.loadNamedSpec(mkspec.toString(), false);
 
     QList<QtVersionFactory *> factories = ExtensionSystem::PluginManager::getObjects<QtVersionFactory>();
diff --git a/src/shared/proparser/profileevaluator.cpp b/src/shared/proparser/profileevaluator.cpp
index 47012d99fdd..c9558519281 100644
--- a/src/shared/proparser/profileevaluator.cpp
+++ b/src/shared/proparser/profileevaluator.cpp
@@ -43,9 +43,9 @@ void ProFileEvaluator::initialize()
     QMakeEvaluator::initStatics();
 }
 
-ProFileEvaluator::ProFileEvaluator(ProFileGlobals *option, QMakeParser *parser,
+ProFileEvaluator::ProFileEvaluator(ProFileGlobals *option, QMakeParser *parser, QMakeVfs *vfs,
                                    QMakeHandler *handler)
-  : d(new QMakeEvaluator(option, parser, handler))
+  : d(new QMakeEvaluator(option, parser, vfs, handler))
 {
 }
 
diff --git a/src/shared/proparser/profileevaluator.h b/src/shared/proparser/profileevaluator.h
index a172536411d..8d6fec86c3d 100644
--- a/src/shared/proparser/profileevaluator.h
+++ b/src/shared/proparser/profileevaluator.h
@@ -40,6 +40,7 @@
 
 QT_BEGIN_NAMESPACE
 
+class QMakeVfs;
 class QMakeParser;
 class QMakeEvaluator;
 class QMakeHandler;
@@ -65,7 +66,8 @@ public:
     // Call this from a concurrency-free context
     static void initialize();
 
-    ProFileEvaluator(ProFileGlobals *option, QMakeParser *parser, QMakeHandler *handler);
+    ProFileEvaluator(ProFileGlobals *option, QMakeParser *parser, QMakeVfs *vfs,
+                     QMakeHandler *handler);
     ~ProFileEvaluator();
 
     ProFileEvaluator::TemplateType templateType() const;
diff --git a/src/shared/proparser/proparser.pri b/src/shared/proparser/proparser.pri
index 900151d75f9..a3667e52919 100644
--- a/src/shared/proparser/proparser.pri
+++ b/src/shared/proparser/proparser.pri
@@ -14,6 +14,7 @@ HEADERS += \
         profileevaluator.h \
         proitems.h \
         prowriter.h \
+        qmakevfs.h \
         ioutils.h
 
 SOURCES += \
@@ -24,6 +25,7 @@ SOURCES += \
         qmakebuiltins.cpp \
         proitems.cpp \
         prowriter.cpp \
+        qmakevfs.cpp \
         ioutils.cpp
 
 RESOURCES += proparser.qrc
diff --git a/src/shared/proparser/qmakebuiltins.cpp b/src/shared/proparser/qmakebuiltins.cpp
index 00f476cb51f..eb58632c84b 100644
--- a/src/shared/proparser/qmakebuiltins.cpp
+++ b/src/shared/proparser/qmakebuiltins.cpp
@@ -32,6 +32,7 @@
 #include "qmakeevaluator_p.h"
 #include "qmakeglobals.h"
 #include "qmakeparser.h"
+#include "qmakevfs.h"
 #include "ioutils.h"
 
 #include <qbytearray.h>
@@ -269,41 +270,12 @@ quoteValue(const ProString &val)
     return ret;
 }
 
-static bool
-doWriteFile(const QString &name, QIODevice::OpenMode mode, const QString &contents, QString *errStr)
-{
-    QByteArray bytes = contents.toLocal8Bit();
-    QFile cfile(name);
-    if (!(mode & QIODevice::Append) && cfile.open(QIODevice::ReadOnly | QIODevice::Text)) {
-        if (cfile.readAll() == bytes)
-            return true;
-        cfile.close();
-    }
-    if (!cfile.open(mode | QIODevice::WriteOnly | QIODevice::Text)) {
-        *errStr = cfile.errorString();
-        return false;
-    }
-    cfile.write(bytes);
-    cfile.close();
-    if (cfile.error() != QFile::NoError) {
-        *errStr = cfile.errorString();
-        return false;
-    }
-    return true;
-}
-
 QMakeEvaluator::VisitReturn
 QMakeEvaluator::writeFile(const QString &ctx, const QString &fn, QIODevice::OpenMode mode,
                           const QString &contents)
 {
-    QFileInfo qfi(fn);
-    if (!QDir::current().mkpath(qfi.path())) {
-        evalError(fL1S("Cannot create %1directory %2.")
-                  .arg(ctx, QDir::toNativeSeparators(qfi.path())));
-        return ReturnFalse;
-    }
     QString errStr;
-    if (!doWriteFile(fn, mode, contents, &errStr)) {
+    if (!m_vfs->writeFile(fn, mode, contents, &errStr)) {
         evalError(fL1S("Cannot write %1file %2: %3.")
                   .arg(ctx, QDir::toNativeSeparators(fn), errStr));
         return ReturnFalse;
@@ -1413,6 +1385,9 @@ QMakeEvaluator::VisitReturn QMakeEvaluator::evaluateBuiltinConditional(
         }
         const QString &file = resolvePath(m_option->expandEnvVars(args.at(0).toQString(m_tmp1)));
 
+        // Don't use VFS here:
+        // - it supports neither listing nor even directories
+        // - it's unlikely that somebody would test for files they created themselves
         if (IoUtils::exists(file))
             return ReturnTrue;
         int slsh = file.lastIndexOf(QLatin1Char('/'));
@@ -1444,7 +1419,6 @@ QMakeEvaluator::VisitReturn QMakeEvaluator::evaluateBuiltinConditional(
             evalError(fL1S("write_file(name, [content var, [append]]) requires one to three arguments."));
             return ReturnFalse;
         }
-#ifdef PROEVALUATOR_FULL
         QIODevice::OpenMode mode = QIODevice::Truncate;
         QString contents;
         if (args.count() >= 2) {
@@ -1456,9 +1430,6 @@ QMakeEvaluator::VisitReturn QMakeEvaluator::evaluateBuiltinConditional(
                     mode = QIODevice::Append;
         }
         return writeFile(QString(), resolvePath(args.at(0).toQString(m_tmp1)), mode, contents);
-#else
-        return ReturnTrue;
-#endif
     }
     case T_TOUCH: {
         if (args.count() != 2) {
@@ -1510,7 +1481,6 @@ QMakeEvaluator::VisitReturn QMakeEvaluator::evaluateBuiltinConditional(
             evalError(fL1S("cache(var, [set|add|sub] [transient] [super], [srcvar]) requires one to three arguments."));
             return ReturnFalse;
         }
-#ifdef PROEVALUATOR_FULL
         bool persist = true;
         bool super = false;
         enum { CacheSet, CacheAdd, CacheSub } mode = CacheSet;
@@ -1636,9 +1606,6 @@ QMakeEvaluator::VisitReturn QMakeEvaluator::evaluateBuiltinConditional(
             fn = m_cachefile;
         }
         return writeFile(fL1S("cache "), fn, QIODevice::Append, varstr);
-#else
-        return ReturnTrue;
-#endif
     }
     default:
         evalError(fL1S("Function '%1' is not implemented.").arg(function.toQString(m_tmp1)));
diff --git a/src/shared/proparser/qmakeevaluator.cpp b/src/shared/proparser/qmakeevaluator.cpp
index 9ba0d70b16a..5a750adbd0d 100644
--- a/src/shared/proparser/qmakeevaluator.cpp
+++ b/src/shared/proparser/qmakeevaluator.cpp
@@ -32,6 +32,7 @@
 
 #include "qmakeglobals.h"
 #include "qmakeparser.h"
+#include "qmakevfs.h"
 #include "ioutils.h"
 
 #include <qbytearray.h>
@@ -162,13 +163,13 @@ const ProKey &QMakeEvaluator::map(const ProKey &var)
 }
 
 
-QMakeEvaluator::QMakeEvaluator(QMakeGlobals *option,
-                               QMakeParser *parser, QMakeHandler *handler)
+QMakeEvaluator::QMakeEvaluator(QMakeGlobals *option, QMakeParser *parser, QMakeVfs *vfs,
+                               QMakeHandler *handler)
   :
 #ifdef PROEVALUATOR_DEBUG
     m_debugLevel(option->debugLevel),
 #endif
-    m_option(option), m_parser(parser), m_handler(handler)
+    m_option(option), m_parser(parser), m_handler(handler), m_vfs(vfs)
 {
     // So that single-threaded apps don't have to call initialize() for now.
     initStatics();
@@ -1049,7 +1050,7 @@ bool QMakeEvaluator::prepareProject(const QString &inDir)
             superdir = m_outputDir;
             forever {
                 QString superfile = superdir + QLatin1String("/.qmake.super");
-                if (IoUtils::exists(superfile)) {
+                if (m_vfs->exists(superfile)) {
                     m_superfile = QDir::cleanPath(superfile);
                     break;
                 }
@@ -1064,10 +1065,10 @@ bool QMakeEvaluator::prepareProject(const QString &inDir)
             QString dir = m_outputDir;
             forever {
                 conffile = sdir + QLatin1String("/.qmake.conf");
-                if (!IoUtils::exists(conffile))
+                if (!m_vfs->exists(conffile))
                     conffile.clear();
                 cachefile = dir + QLatin1String("/.qmake.cache");
-                if (!IoUtils::exists(cachefile))
+                if (!m_vfs->exists(cachefile))
                     cachefile.clear();
                 if (!conffile.isEmpty() || !cachefile.isEmpty()) {
                     if (dir != sdir)
@@ -1158,7 +1159,7 @@ bool QMakeEvaluator::loadSpec()
                 m_hostBuild ? m_option->qmakespec : m_option->xqmakespec);
 
     {
-        QMakeEvaluator evaluator(m_option, m_parser, m_handler);
+        QMakeEvaluator evaluator(m_option, m_parser, m_vfs, m_handler);
         if (!m_superfile.isEmpty()) {
             valuesRef(ProKey("_QMAKE_SUPER_CACHE_")) << ProString(m_superfile);
             if (evaluator.evaluateFile(
@@ -1315,7 +1316,7 @@ QMakeEvaluator::VisitReturn QMakeEvaluator::visitProFile(
                 locker.unlock();
 #endif
 
-                QMakeEvaluator *baseEval = new QMakeEvaluator(m_option, m_parser, m_handler);
+                QMakeEvaluator *baseEval = new QMakeEvaluator(m_option, m_parser, m_vfs, m_handler);
                 baseEnv->evaluator = baseEval;
                 baseEval->m_superfile = m_superfile;
                 baseEval->m_conffile = m_conffile;
@@ -1810,7 +1811,7 @@ QMakeEvaluator::VisitReturn QMakeEvaluator::evaluateFile(
 #endif
         return ok;
     } else {
-        if (!(flags & LoadSilent) && !IoUtils::exists(fileName))
+        if (!(flags & LoadSilent) && !m_vfs->exists(fileName))
             evalError(fL1S("WARNING: Include file %1 not found").arg(fileName));
         return ReturnFalse;
     }
@@ -1893,7 +1894,7 @@ QMakeEvaluator::VisitReturn QMakeEvaluator::evaluateFeatureFile(
 QMakeEvaluator::VisitReturn QMakeEvaluator::evaluateFileInto(
         const QString &fileName, ProValueMap *values, LoadFlags flags)
 {
-    QMakeEvaluator visitor(m_option, m_parser, m_handler);
+    QMakeEvaluator visitor(m_option, m_parser, m_vfs, m_handler);
     visitor.m_caller = this;
     visitor.m_outputDir = m_outputDir;
     visitor.m_featureRoots = m_featureRoots;
diff --git a/src/shared/proparser/qmakeevaluator.h b/src/shared/proparser/qmakeevaluator.h
index 63d34e8f764..4d2e7c7693a 100644
--- a/src/shared/proparser/qmakeevaluator.h
+++ b/src/shared/proparser/qmakeevaluator.h
@@ -96,7 +96,7 @@ public:
 
     static void initStatics();
     static void initFunctionStatics();
-    QMakeEvaluator(QMakeGlobals *option, QMakeParser *parser,
+    QMakeEvaluator(QMakeGlobals *option, QMakeParser *parser, QMakeVfs *vfs,
                    QMakeHandler *handler);
     ~QMakeEvaluator();
 
@@ -282,6 +282,7 @@ public:
     QMakeGlobals *m_option;
     QMakeParser *m_parser;
     QMakeHandler *m_handler;
+    QMakeVfs *m_vfs;
 };
 
 Q_DECLARE_OPERATORS_FOR_FLAGS(QMakeEvaluator::LoadFlags)
diff --git a/src/shared/proparser/qmakeparser.cpp b/src/shared/proparser/qmakeparser.cpp
index ae0fdd0fac5..9dd10ac448e 100644
--- a/src/shared/proparser/qmakeparser.cpp
+++ b/src/shared/proparser/qmakeparser.cpp
@@ -29,6 +29,7 @@
 
 #include "qmakeparser.h"
 
+#include "qmakevfs.h"
 #include "ioutils.h"
 using namespace QMakeInternal;
 
@@ -130,9 +131,10 @@ void QMakeParser::initialize()
     statics.strLITERAL_WHITESPACE = QLatin1String("LITERAL_WHITESPACE");
 }
 
-QMakeParser::QMakeParser(ProFileCache *cache, QMakeParserHandler *handler)
+QMakeParser::QMakeParser(ProFileCache *cache, QMakeVfs *vfs, QMakeParserHandler *handler)
     : m_cache(cache)
     , m_handler(handler)
+    , m_vfs(vfs)
 {
     // So that single-threaded apps don't have to call initialize() for now.
     initialize();
@@ -218,24 +220,14 @@ void QMakeParser::discardFileFromCache(const QString &fileName)
 
 bool QMakeParser::read(ProFile *pro)
 {
-    QFile file(pro->fileName());
-    if (!file.open(QIODevice::ReadOnly)) {
-        if (m_handler && IoUtils::exists(pro->fileName()))
+    QString content;
+    QString errStr;
+    if (!m_vfs->readFile(pro->fileName(), &content, &errStr)) {
+        if (m_handler && m_vfs->exists(pro->fileName()))
             m_handler->message(QMakeParserHandler::ParserIoError,
-                               fL1S("Cannot read %1: %2").arg(pro->fileName(), file.errorString()));
+                               fL1S("Cannot read %1: %2").arg(pro->fileName(), errStr));
         return false;
     }
-
-    QByteArray bcont = file.readAll();
-    if (bcont.startsWith("\xef\xbb\xbf")) {
-        // UTF-8 BOM will cause subtle errors
-        m_handler->message(QMakeParserHandler::ParserIoError,
-                           fL1S("Unexpected UTF-8 BOM in %1").arg(pro->fileName()));
-        return false;
-    }
-    QString content(QString::fromLocal8Bit(bcont));
-    bcont.clear();
-    file.close();
     return read(pro, content, 1, FullGrammar);
 }
 
diff --git a/src/shared/proparser/qmakeparser.h b/src/shared/proparser/qmakeparser.h
index 6fc599f617d..87cd8c2244a 100644
--- a/src/shared/proparser/qmakeparser.h
+++ b/src/shared/proparser/qmakeparser.h
@@ -67,6 +67,7 @@ public:
 };
 
 class ProFileCache;
+class QMakeVfs;
 
 class QMAKE_EXPORT QMakeParser
 {
@@ -74,7 +75,7 @@ public:
     // Call this from a concurrency-free context
     static void initialize();
 
-    QMakeParser(ProFileCache *cache, QMakeParserHandler *handler);
+    QMakeParser(ProFileCache *cache, QMakeVfs *vfs, QMakeParserHandler *handler);
 
     enum SubGrammar { FullGrammar, TestGrammar, ValueGrammar };
     // fileName is expected to be absolute and cleanPath()ed.
@@ -163,6 +164,7 @@ private:
 
     ProFileCache *m_cache;
     QMakeParserHandler *m_handler;
+    QMakeVfs *m_vfs;
 
     // This doesn't help gcc 3.3 ...
     template<typename T> friend class QTypeInfo;
diff --git a/src/shared/proparser/qmakevfs.cpp b/src/shared/proparser/qmakevfs.cpp
new file mode 100644
index 00000000000..69373c4a9e4
--- /dev/null
+++ b/src/shared/proparser/qmakevfs.cpp
@@ -0,0 +1,178 @@
+/****************************************************************************
+**
+** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of Qt Creator.
+**
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+****************************************************************************/
+
+#include "qmakevfs.h"
+
+#include "ioutils.h"
+using namespace QMakeInternal;
+
+#include <qdir.h>
+#include <qfile.h>
+#include <qfileinfo.h>
+
+#define fL1S(s) QString::fromLatin1(s)
+
+QMakeVfs::QMakeVfs()
+#ifndef PROEVALUATOR_FULL
+    : m_magicMissing(fL1S("missing"))
+    , m_magicExisting(fL1S("existing"))
+#endif
+{
+}
+
+bool QMakeVfs::writeFile(const QString &fn, QIODevice::OpenMode mode, const QString &contents,
+                         QString *errStr)
+{
+#ifndef PROEVALUATOR_FULL
+# ifdef PROEVALUATOR_THREAD_SAFE
+    QMutexLocker locker(&m_mutex);
+# endif
+    QString *cont = &m_files[fn];
+    if (mode & QIODevice::Append)
+        *cont += contents;
+    else
+        *cont = contents;
+    Q_UNUSED(errStr)
+    return true;
+#else
+    QFileInfo qfi(fn);
+    if (!QDir::current().mkpath(qfi.path())) {
+        *errStr = fL1S("Cannot create parent directory");
+        return false;
+    }
+    QByteArray bytes = contents.toLocal8Bit();
+    QFile cfile(fn);
+    if (!(mode & QIODevice::Append) && cfile.open(QIODevice::ReadOnly | QIODevice::Text)) {
+        if (cfile.readAll() == bytes)
+            return true;
+        cfile.close();
+    }
+    if (!cfile.open(mode | QIODevice::WriteOnly | QIODevice::Text)) {
+        *errStr = cfile.errorString();
+        return false;
+    }
+    cfile.write(bytes);
+    cfile.close();
+    if (cfile.error() != QFile::NoError) {
+        *errStr = cfile.errorString();
+        return false;
+    }
+    return true;
+#endif
+}
+
+bool QMakeVfs::readFile(const QString &fn, QString *contents, QString *errStr)
+{
+#ifndef PROEVALUATOR_FULL
+# ifdef PROEVALUATOR_THREAD_SAFE
+    QMutexLocker locker(&m_mutex);
+# endif
+    QHash<QString, QString>::ConstIterator it = m_files.constFind(fn);
+    if (it != m_files.constEnd()) {
+        if (it->constData() == m_magicMissing.constData()) {
+            *errStr = fL1S("No such file or directory");
+            return false;
+        }
+        if (it->constData() != m_magicExisting.constData()) {
+            *contents = *it;
+            return true;
+        }
+    }
+#endif
+
+    QFile file(fn);
+    if (!file.open(QIODevice::ReadOnly)) {
+#ifndef PROEVALUATOR_FULL
+        if (!IoUtils::exists(fn)) {
+            m_files[fn] = m_magicMissing;
+            *errStr = fL1S("No such file or directory");
+        } else
+#endif
+            *errStr = file.errorString();
+        return false;
+    }
+#ifndef PROEVALUATOR_FULL
+    m_files[fn] = m_magicExisting;
+#endif
+
+    QByteArray bcont = file.readAll();
+    if (bcont.startsWith("\xef\xbb\xbf")) {
+        // UTF-8 BOM will cause subtle errors
+        *errStr = fL1S("Unexpected UTF-8 BOM");
+        return false;
+    }
+    *contents = QString::fromLocal8Bit(bcont);
+    return true;
+}
+
+bool QMakeVfs::exists(const QString &fn)
+{
+#ifndef PROEVALUATOR_FULL
+# ifdef PROEVALUATOR_THREAD_SAFE
+    QMutexLocker locker(&m_mutex);
+# endif
+    QHash<QString, QString>::ConstIterator it = m_files.constFind(fn);
+    if (it != m_files.constEnd())
+        return it->constData() != m_magicMissing.constData();
+#endif
+    bool ex = IoUtils::exists(fn);
+#ifndef PROEVALUATOR_FULL
+    m_files[fn] = ex ? m_magicExisting : m_magicMissing;
+#endif
+    return ex;
+}
+
+#ifndef PROEVALUATOR_FULL
+// This should be called when the sources may have changed (e.g., VCS update).
+void QMakeVfs::invalidateCache()
+{
+# ifdef PROEVALUATOR_THREAD_SAFE
+    QMutexLocker locker(&m_mutex);
+# endif
+    QHash<QString, QString>::Iterator it = m_files.begin(), eit = m_files.end();
+    while (it != eit) {
+        if (it->constData() == m_magicMissing.constData()
+                ||it->constData() == m_magicExisting.constData())
+            it = m_files.erase(it);
+        else
+            ++it;
+    }
+}
+
+// This should be called when generated files may have changed (e.g., actual build).
+void QMakeVfs::invalidateContents()
+{
+# ifdef PROEVALUATOR_THREAD_SAFE
+    QMutexLocker locker(&m_mutex);
+# endif
+    m_files.clear();
+}
+#endif
+
+QT_END_NAMESPACE
diff --git a/src/shared/proparser/qmakevfs.h b/src/shared/proparser/qmakevfs.h
new file mode 100644
index 00000000000..045765a3629
--- /dev/null
+++ b/src/shared/proparser/qmakevfs.h
@@ -0,0 +1,73 @@
+/****************************************************************************
+**
+** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of Qt Creator.
+**
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+****************************************************************************/
+
+#ifndef QMAKEVFS_H
+#define QMAKEVFS_H
+
+#include "qmake_global.h"
+
+# include <QIODevice>
+#ifndef PROEVALUATOR_FULL
+# include <QHash>
+# include <QString>
+# ifdef PROEVALUATOR_THREAD_SAFE
+#  include <qmutex.h>
+# endif
+#endif
+
+QT_BEGIN_NAMESPACE
+
+class QMAKE_EXPORT QMakeVfs
+{
+public:
+    QMakeVfs();
+
+    bool writeFile(const QString &fn, QIODevice::OpenMode mode, const QString &contents, QString *errStr);
+    bool readFile(const QString &fn, QString *contents, QString *errStr);
+    bool exists(const QString &fn);
+
+#ifndef PROEVALUATOR_FULL
+    void invalidateCache();
+    void invalidateContents();
+#endif
+
+private:
+#ifndef PROEVALUATOR_FULL
+# ifdef PROEVALUATOR_THREAD_SAFE
+    QMutex m_mutex;
+# endif
+    QHash<QString, QString> m_files;
+    QString m_magicMissing;
+    QString m_magicExisting;
+#endif
+};
+
+QT_END_NAMESPACE
+
+#endif // QMAKEVFS_H
diff --git a/tests/auto/profilewriter/tst_profilewriter.cpp b/tests/auto/profilewriter/tst_profilewriter.cpp
index cf31b48efe5..4dd71629b8e 100644
--- a/tests/auto/profilewriter/tst_profilewriter.cpp
+++ b/tests/auto/profilewriter/tst_profilewriter.cpp
@@ -27,6 +27,7 @@
 **
 ****************************************************************************/
 
+#include <qmakevfs.h>
 #include <qmakeparser.h>
 #include <prowriter.h>
 
@@ -449,7 +450,8 @@ void tst_ProFileWriter::adds()
     QStringList lines = input.isEmpty() ? QStringList() : input.split(QLatin1String("\n"));
     QString var = QLatin1String("SOURCES");
 
-    QMakeParser parser(0, &parseHandler);
+    QMakeVfs vfs;
+    QMakeParser parser(0, &vfs, &parseHandler);
     ProFile *proFile = parser.parsedProBlock(input, QLatin1String(BASE_DIR "/test.pro"), 1);
     QVERIFY(proFile);
     PW::putVarValues(proFile, &lines, values, var, PW::PutFlags(flags), scope);
@@ -619,7 +621,8 @@ void tst_ProFileWriter::removes()
     QStringList lines = input.split(QLatin1String("\n"));
     QStringList vars; vars << QLatin1String("SOURCES");
 
-    QMakeParser parser(0, &parseHandler);
+    QMakeVfs vfs;
+    QMakeParser parser(0, &vfs, &parseHandler);
     ProFile *proFile = parser.parsedProBlock(input, QLatin1String(BASE_DIR "/test.pro"), 1);
     QVERIFY(proFile);
     Qt4ProjectManager::Internal::ProWriter::removeVarValues(proFile, &lines, values, vars);
@@ -647,7 +650,8 @@ void tst_ProFileWriter::multiVar()
             << QString::fromLatin1(BASE_DIR "/bak");
     QStringList vars; vars << QLatin1String("SOURCES") << QLatin1String("HEADERS");
 
-    QMakeParser parser(0, &parseHandler);
+    QMakeVfs vfs;
+    QMakeParser parser(0, &vfs, &parseHandler);
     ProFile *proFile = parser.parsedProBlock(input, QLatin1String(BASE_DIR "/test.pro"), 1);
     QVERIFY(proFile);
     Qt4ProjectManager::Internal::ProWriter::removeFiles(proFile, &lines, baseDir, files, vars);
@@ -667,7 +671,8 @@ void tst_ProFileWriter::addFiles()
             "    sub/bar.cpp"
             );
 
-    QMakeParser parser(0, &parseHandler);
+    QMakeVfs vfs;
+    QMakeParser parser(0, &vfs, &parseHandler);
     ProFile *proFile = parser.parsedProBlock(input, QLatin1String(BASE_DIR "/test.pro"), 1);
     QVERIFY(proFile);
     Qt4ProjectManager::Internal::ProWriter::addFiles(proFile, &lines, QDir(BASE_DIR),
@@ -688,7 +693,8 @@ void tst_ProFileWriter::removeFiles()
             "SOURCES = foo.cpp"
             );
 
-    QMakeParser parser(0, &parseHandler);
+    QMakeVfs vfs;
+    QMakeParser parser(0, &vfs, &parseHandler);
     ProFile *proFile = parser.parsedProBlock(input, QLatin1String(BASE_DIR "/test.pro"), 1);
     QVERIFY(proFile);
     Qt4ProjectManager::Internal::ProWriter::removeFiles(proFile, &lines, QDir(BASE_DIR),
diff --git a/tests/manual/proparser/main.cpp b/tests/manual/proparser/main.cpp
index 36ee676106c..c7b5d972327 100644
--- a/tests/manual/proparser/main.cpp
+++ b/tests/manual/proparser/main.cpp
@@ -28,6 +28,7 @@
 ****************************************************************************/
 
 #include "qmakeglobals.h"
+#include "qmakevfs.h"
 #include "qmakeparser.h"
 #include "qmakeevaluator.h"
 #include "profileevaluator.h"
@@ -69,14 +70,15 @@ public:
 static EvalHandler evalHandler;
 
 static int evaluate(const QString &fileName, const QString &in_pwd, const QString &out_pwd,
-                    bool cumulative, ProFileGlobals *option, QMakeParser *parser, int level)
+                    bool cumulative, ProFileGlobals *option, QMakeParser *parser, QMakeVfs *vfs,
+                    int level)
 {
     static QSet<QString> visited;
     if (visited.contains(fileName))
         return 0;
     visited.insert(fileName);
 
-    ProFileEvaluator visitor(option, parser, &evalHandler);
+    ProFileEvaluator visitor(option, parser, vfs, &evalHandler);
 #ifdef PROEVALUATOR_CUMULATIVE
     visitor.setCumulative(cumulative);
 #endif
@@ -130,7 +132,7 @@ static int evaluate(const QString &fileName, const QString &in_pwd, const QStrin
                 fflush(stdout);
                 nlevel++;
             }
-            evaluate(inFile, inPwd, outPwd, cumulative, option, parser, nlevel);
+            evaluate(inFile, inPwd, outPwd, cumulative, option, parser, vfs, nlevel);
         }
     }
 
@@ -195,6 +197,7 @@ int main(int argc, char **argv)
         out_pwd = in_pwd;
     option.setDirectories(in_pwd, out_pwd);
 
-    QMakeParser parser(0, &evalHandler);
-    return evaluate(file, in_pwd, out_pwd, cumulative, &option, &parser, level);
+    QMakeVfs vfs;
+    QMakeParser parser(0, &vfs, &evalHandler);
+    return evaluate(file, in_pwd, out_pwd, cumulative, &option, &parser, &vfs, level);
 }
diff --git a/tests/manual/proparser/testreader.pro b/tests/manual/proparser/testreader.pro
index 6d58c9e257d..022ac67667c 100644
--- a/tests/manual/proparser/testreader.pro
+++ b/tests/manual/proparser/testreader.pro
@@ -15,8 +15,27 @@ build_all:!build_pass {
     CONFIG += release
 }
 
-SOURCES = main.cpp qmakeglobals.cpp qmakeparser.cpp qmakeevaluator.cpp profileevaluator.cpp qmakebuiltins.cpp proitems.cpp ioutils.cpp
-HEADERS = qmakeglobals.h qmakeparser.h profileevaluator.h qmakeevaluator.h qmakeevaluator_p.h proitems.h ioutils.h
+SOURCES += \
+    main.cpp \
+    qmakeglobals.cpp \
+    qmakeparser.cpp \
+    qmakeevaluator.cpp \
+    profileevaluator.cpp \
+    qmakebuiltins.cpp \
+    proitems.cpp \
+    qmakevfs.cpp \
+    ioutils.cpp
+
+HEADERS += \
+    qmake_global.h \
+    qmakeglobals.h \
+    qmakeparser.h \
+    qmakeevaluator.h \
+    qmakeevaluator_p.h \
+    profileevaluator.h \
+    proitems.h \
+    qmakevfs.h \
+    ioutils.h
 
 RESOURCES += proparser.qrc
 DEFINES += QMAKE_BUILTIN_PRFS