diff --git a/src/corelib/io/io.pri b/src/corelib/io/io.pri
index fe81689932..c4c6f41387 100644
--- a/src/corelib/io/io.pri
+++ b/src/corelib/io/io.pri
@@ -136,6 +136,7 @@ qtConfig(settings) {
     } else: darwin:!nacl {
         SOURCES += io/qsettings_mac.cpp
     }
+    wasm : SOURCES += io/qsettings_wasm.cpp
 }
 
 win32 {
diff --git a/src/corelib/io/qsettings.cpp b/src/corelib/io/qsettings.cpp
index fc7122d904..dcc9340473 100644
--- a/src/corelib/io/qsettings.cpp
+++ b/src/corelib/io/qsettings.cpp
@@ -76,10 +76,6 @@
 #  include <ioLib.h>
 #endif
 
-#ifdef Q_OS_WASM
-#include <emscripten.h>
-#endif
-
 #include <algorithm>
 #include <stdlib.h>
 
@@ -295,7 +291,7 @@ after_loop:
 
 // see also qsettings_win.cpp, qsettings_winrt.cpp and qsettings_mac.cpp
 
-#if !defined(Q_OS_WIN) && !defined(Q_OS_MAC)
+#if !defined(Q_OS_WIN) && !defined(Q_OS_MAC) && !defined(Q_OS_WASM)
 QSettingsPrivate *QSettingsPrivate::create(QSettings::Format format, QSettings::Scope scope,
                                            const QString &organization, const QString &application)
 {
@@ -1185,7 +1181,9 @@ QConfFileSettingsPrivate::QConfFileSettingsPrivate(QSettings::Format format,
         confFiles.append(QConfFile::fromName(systemPath.path + orgFile, false));
     }
 
+#ifndef Q_OS_WASM // wasm needs to delay access until after file sync
     initAccess();
+#endif
 }
 
 QConfFileSettingsPrivate::QConfFileSettingsPrivate(const QString &fileName,
@@ -1548,13 +1546,6 @@ void QConfFileSettingsPrivate::syncConfFile(QConfFile *confFile)
                     perms |= QFile::ReadGroup | QFile::ReadOther;
                 QFile(confFile->name).setPermissions(perms);
             }
-#ifdef Q_OS_WASM
-        EM_ASM(
-            // Sync sandbox filesystem to persistent database filesystem. See QTBUG-70002
-            FS.syncfs(false, function(err) {
-            });
-        );
-#endif
         } else {
             setStatus(QSettings::AccessError);
         }
diff --git a/src/corelib/io/qsettings_p.h b/src/corelib/io/qsettings_p.h
index d18c96a06c..c30f099a72 100644
--- a/src/corelib/io/qsettings_p.h
+++ b/src/corelib/io/qsettings_p.h
@@ -57,6 +57,10 @@
 #include "QtCore/qiodevice.h"
 #include "QtCore/qstack.h"
 #include "QtCore/qstringlist.h"
+
+#include <QtCore/qvariant.h>
+#include "qsettings.h"
+
 #ifndef QT_NO_QOBJECT
 #include "private/qobject_p.h"
 #endif
@@ -253,6 +257,10 @@ protected:
     mutable QSettings::Status status;
 };
 
+#ifdef Q_OS_WASM
+class QWasmSettingsPrivate;
+#endif
+
 class QConfFileSettingsPrivate : public QSettingsPrivate
 {
 public:
@@ -281,7 +289,7 @@ public:
 
 private:
     void initFormat();
-    void initAccess();
+    virtual void initAccess();
     void syncConfFile(QConfFile *confFile);
     bool writeIniFile(QIODevice &device, const ParsedSettingsMap &map);
 #ifdef Q_OS_MAC
@@ -297,6 +305,9 @@ private:
     QString extension;
     Qt::CaseSensitivity caseSensitivity;
     int nextPosition;
+#ifdef Q_OS_WASM
+    friend class QWasmSettingsPrivate;
+#endif
 };
 
 QT_END_NAMESPACE
diff --git a/src/corelib/io/qsettings_wasm.cpp b/src/corelib/io/qsettings_wasm.cpp
new file mode 100644
index 0000000000..8d8f4b505c
--- /dev/null
+++ b/src/corelib/io/qsettings_wasm.cpp
@@ -0,0 +1,259 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtCore module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** 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 The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/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 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qsettings.h"
+#ifndef QT_NO_SETTINGS
+
+#include "qsettings_p.h"
+#ifndef QT_NO_QOBJECT
+#include "qcoreapplication.h"
+#include <QFile>
+#endif // QT_NO_QOBJECT
+#include <QDebug>
+
+#include <QFileInfo>
+#include <QDir>
+#include <emscripten.h>
+
+QT_BEGIN_NAMESPACE
+
+static bool isReadReady = false;
+
+class QWasmSettingsPrivate : public QConfFileSettingsPrivate
+{
+public:
+    QWasmSettingsPrivate(QSettings::Scope scope, const QString &organization,
+                        const QString &application);
+    ~QWasmSettingsPrivate();
+
+    bool get(const QString &key, QVariant *value) const override;
+    QStringList children(const QString &prefix, ChildSpec spec) const override;
+    void clear() override;
+    void sync() override;
+    void flush() override;
+    bool isWritable() const override;
+
+    void syncToLocal(const char *data, int size);
+    void loadLocal(const QByteArray &filename);
+    void setReady();
+    void initAccess() override;
+
+private:
+    QString databaseName;
+    QString id;
+};
+
+static void QWasmSettingsPrivate_onLoad(void *userData, void *dataPtr, int size)
+{
+    QWasmSettingsPrivate *wasm = reinterpret_cast<QWasmSettingsPrivate *>(userData);
+
+    QFile file(wasm->fileName());
+    QFileInfo fileInfo(wasm->fileName());
+    QDir dir(fileInfo.path());
+    if (!dir.exists())
+        dir.mkpath(fileInfo.path());
+
+    if (file.open(QFile::WriteOnly)) {
+        file.write(reinterpret_cast<char *>(dataPtr), size);
+        file.close();
+        wasm->setReady();
+    }
+}
+
+static void QWasmSettingsPrivate_onError(void *userData)
+{
+    QWasmSettingsPrivate *wasm = reinterpret_cast<QWasmSettingsPrivate *>(userData);
+    if (wasm)
+        wasm->setStatus(QSettings::AccessError);
+}
+
+static void QWasmSettingsPrivate_onStore(void *userData)
+{
+    QWasmSettingsPrivate *wasm = reinterpret_cast<QWasmSettingsPrivate *>(userData);
+    if (wasm)
+        wasm->setStatus(QSettings::NoError);
+}
+
+static void QWasmSettingsPrivate_onCheck(void *userData, int exists)
+{
+    QWasmSettingsPrivate *wasm = reinterpret_cast<QWasmSettingsPrivate *>(userData);
+    if (wasm) {
+        if (exists)
+            wasm->loadLocal(wasm->fileName().toLocal8Bit());
+        else
+            wasm->setReady();
+    }
+}
+
+QSettingsPrivate *QSettingsPrivate::create(QSettings::Format format,
+                                           QSettings::Scope scope,
+                                           const QString &organization,
+                                           const QString &application)
+{
+    Q_UNUSED(format)
+    if (organization == QLatin1String("Qt"))
+    {
+        QString organizationDomain = QCoreApplication::organizationDomain();
+        QString applicationName = QCoreApplication::applicationName();
+
+        QSettingsPrivate *newSettings;
+        newSettings = new QWasmSettingsPrivate(scope, organizationDomain, applicationName);
+
+        newSettings->beginGroupOrArray(QSettingsGroup(normalizedKey(organization)));
+        if (!application.isEmpty())
+            newSettings->beginGroupOrArray(QSettingsGroup(normalizedKey(application)));
+
+        return newSettings;
+    }
+    return new QWasmSettingsPrivate(scope, organization, application);
+}
+
+QWasmSettingsPrivate::QWasmSettingsPrivate(QSettings::Scope scope, const QString &organization,
+                                           const QString &application)
+    : QConfFileSettingsPrivate(QSettings::NativeFormat, scope, organization, application)
+{
+    setStatus(QSettings::AccessError); // access error until sandbox gets loaded
+    databaseName = organization;
+    id = application;
+
+    emscripten_idb_async_exists("/home/web_user",
+                                fileName().toLocal8Bit(),
+                                reinterpret_cast<void*>(this),
+                                QWasmSettingsPrivate_onCheck,
+                                QWasmSettingsPrivate_onError);
+}
+
+QWasmSettingsPrivate::~QWasmSettingsPrivate()
+{
+}
+
+ void QWasmSettingsPrivate::initAccess()
+{
+     if (isReadReady)
+         QConfFileSettingsPrivate::initAccess();
+}
+
+bool QWasmSettingsPrivate::get(const QString &key, QVariant *value) const
+{
+    if (isReadReady)
+        return QConfFileSettingsPrivate::get(key, value);
+
+    return false;
+}
+
+QStringList QWasmSettingsPrivate::children(const QString &prefix, ChildSpec spec) const
+{
+    return QConfFileSettingsPrivate::children(prefix, spec);
+}
+
+void QWasmSettingsPrivate::clear()
+{
+    QConfFileSettingsPrivate::clear();
+    emscripten_idb_async_delete("/home/web_user",
+                                fileName().toLocal8Bit(),
+                                reinterpret_cast<void*>(this),
+                                QWasmSettingsPrivate_onStore,
+                                QWasmSettingsPrivate_onError);
+}
+
+void QWasmSettingsPrivate::sync()
+{
+    QConfFileSettingsPrivate::sync();
+
+    QFile file(fileName());
+    if (file.open(QFile::ReadOnly)) {
+        QByteArray dataPointer = file.readAll();
+
+        emscripten_idb_async_store("/home/web_user",
+                                  fileName().toLocal8Bit(),
+                                   reinterpret_cast<void *>(dataPointer.data()),
+                                   dataPointer.length(),
+                                   reinterpret_cast<void*>(this),
+                                   QWasmSettingsPrivate_onStore,
+                                   QWasmSettingsPrivate_onError);
+    }
+}
+
+void QWasmSettingsPrivate::flush()
+{
+    sync();
+}
+
+bool QWasmSettingsPrivate::isWritable() const
+{
+    return isReadReady && QConfFileSettingsPrivate::isWritable();
+}
+
+void QWasmSettingsPrivate::syncToLocal(const char *data, int size)
+{
+    QFile file(fileName());
+
+    if (file.open(QFile::WriteOnly)) {
+        file.write(data, size + 1);
+        QByteArray data = file.readAll();
+
+        emscripten_idb_async_store("/home/web_user",
+                                   fileName().toLocal8Bit(),
+                                   reinterpret_cast<void *>(data.data()),
+                                   data.length(),
+                                   reinterpret_cast<void*>(this),
+                                   QWasmSettingsPrivate_onStore,
+                                   QWasmSettingsPrivate_onError);
+        setReady();
+    }
+}
+
+void QWasmSettingsPrivate::loadLocal(const QByteArray &filename)
+{
+    emscripten_idb_async_load("/home/web_user",
+                              filename.data(),
+                              reinterpret_cast<void*>(this),
+                              QWasmSettingsPrivate_onLoad,
+                              QWasmSettingsPrivate_onError);
+}
+
+void QWasmSettingsPrivate::setReady()
+{
+    isReadReady = true;
+    setStatus(QSettings::NoError);
+    QConfFileSettingsPrivate::initAccess();
+}
+
+QT_END_NAMESPACE
+#endif // QT_NO_SETTINGS
diff --git a/src/corelib/kernel/qcoreapplication.cpp b/src/corelib/kernel/qcoreapplication.cpp
index 6d95979f76..32efa727b8 100644
--- a/src/corelib/kernel/qcoreapplication.cpp
+++ b/src/corelib/kernel/qcoreapplication.cpp
@@ -121,7 +121,6 @@
 #endif
 
 #ifdef Q_OS_WASM
-#include <emscripten.h>
 #include <emscripten/val.h>
 #endif
 
@@ -480,13 +479,6 @@ QCoreApplicationPrivate::QCoreApplicationPrivate(int &aargc, char **aargv, uint
 
 QCoreApplicationPrivate::~QCoreApplicationPrivate()
 {
-#ifdef Q_OS_WASM
-    EM_ASM(
-        // unmount persistent directory as IDBFS
-        // see also QTBUG-70002
-        FS.unmount('/home/web_user');
-    );
-#endif
 #ifndef QT_NO_QOBJECT
     cleanupThreadData();
 #endif
@@ -780,17 +772,8 @@ void QCoreApplicationPrivate::init()
     Q_ASSERT_X(!QCoreApplication::self, "QCoreApplication", "there should be only one application object");
     QCoreApplication::self = q;
 
-#ifdef Q_OS_WASM
-    EM_ASM(
-        // mount and sync persistent filesystem to sandbox
-        FS.mount(IDBFS, {}, '/home/web_user');
-        FS.syncfs(true, function(err) {
-            if (err)
-                Module.print(err);
-        });
-    );
-
 #if QT_CONFIG(thread)
+#ifdef Q_OS_WASM
     QThreadPrivate::idealThreadCount = emscripten::val::global("navigator")["hardwareConcurrency"].as<int>();
 #endif
 #endif
diff --git a/src/gui/kernel/qguiapplication.cpp b/src/gui/kernel/qguiapplication.cpp
index f09f7e941b..455de52319 100644
--- a/src/gui/kernel/qguiapplication.cpp
+++ b/src/gui/kernel/qguiapplication.cpp
@@ -1696,13 +1696,7 @@ QGuiApplicationPrivate::~QGuiApplicationPrivate()
         qt_gl_set_global_share_context(0);
     }
 #endif
-#ifdef Q_OS_WASM
-    EM_ASM(
-        // unmount persistent directory as IDBFS
-        // see QTBUG-70002
-        FS.unmount('/home/web_user');
-    );
-#endif
+
     platform_integration->destroy();
 
     delete platform_theme;