diff --git a/abstract_output.h b/abstract_output.h
--- a/abstract_output.h
+++ b/abstract_output.h
@@ -117,6 +117,15 @@
         return false;
     }
 
+    /**
+     * @returns the angle to rotate the display to fit the output
+     **/
+    virtual int softwareRotationAngle() const {
+        return 0;
+    }
+
+    QSize orientateSize(const QSize &size) const;
+
 Q_SIGNALS:
     void modeChanged();
 
@@ -171,8 +180,6 @@
 
     void setWaylandMode(const QSize &size, int refreshRate);
 
-    QSize orientateSize(const QSize &size) const;
-
 private:
     QPointer<KWayland::Server::OutputInterface> m_waylandOutput;
     QPointer<KWayland::Server::XdgOutputInterface> m_xdgOutput;
diff --git a/abstract_output.cpp b/abstract_output.cpp
--- a/abstract_output.cpp
+++ b/abstract_output.cpp
@@ -54,7 +54,7 @@
 
 QRect AbstractOutput::geometry() const
 {
-    return QRect(m_globalPos, pixelSize() / scale());
+    return QRect(m_globalPos, orientateSize(pixelSize()) / scale());
 }
 
 QSize AbstractOutput::physicalSize() const
@@ -101,7 +101,7 @@
         m_waylandOutputDevice->setScaleF(scale);
     }
     if (m_xdgOutput) {
-        m_xdgOutput->setLogicalSize(pixelSize() / m_scale);
+        m_xdgOutput->setLogicalSize(orientateSize(pixelSize()) / m_scale);
         m_xdgOutput->done();
     }
     emit modeChanged();
@@ -160,7 +160,7 @@
     }
     m_waylandOutput->setCurrentMode(size, refreshRate);
     if (m_xdgOutput) {
-        m_xdgOutput->setLogicalSize(pixelSize() / scale());
+        m_xdgOutput->setLogicalSize(orientateSize(pixelSize()) / scale());
         m_xdgOutput->done();
     }
 }
diff --git a/autotests/mock_screens.h b/autotests/mock_screens.h
--- a/autotests/mock_screens.h
+++ b/autotests/mock_screens.h
@@ -37,6 +37,7 @@
     float refreshRate(int screen) const override;
     QSize size(int screen) const override;
     void init() override;
+    int rotation(int /*screen*/) const override { return 0; }
 
     void setGeometries(const QList<QRect> &geometries);
 
diff --git a/outputscreens.h b/outputscreens.h
--- a/outputscreens.h
+++ b/outputscreens.h
@@ -43,6 +43,7 @@
     QSize size(int screen) const override;
     qreal scale(int screen) const override;
     float refreshRate(int screen) const override;
+    int rotation(int screen) const override;
     Qt::ScreenOrientation orientation(int screen) const override;
     void updateCount() override;
     int number(const QPoint &pos) const override;
diff --git a/outputscreens.cpp b/outputscreens.cpp
--- a/outputscreens.cpp
+++ b/outputscreens.cpp
@@ -110,6 +110,14 @@
     }
     return enOuts.at(screen)->orientation();
 }
+int OutputScreens::rotation(int screen) const
+{
+    auto output = m_platform->enabledOutputs().value(screen, nullptr);
+    if (!output) {
+        return 0;
+    }
+    return output->softwareRotationAngle();
+}
 
 void OutputScreens::updateCount()
 {
diff --git a/platform.h b/platform.h
--- a/platform.h
+++ b/platform.h
@@ -449,6 +449,8 @@
         m_selectedCompositor = type;
     }
 
+    virtual QVector<int> screenRotations() const;
+
 public Q_SLOTS:
     void pointerMotion(const QPointF &position, quint32 time);
     void pointerButtonPressed(quint32 button, quint32 time);
diff --git a/platform.cpp b/platform.cpp
--- a/platform.cpp
+++ b/platform.cpp
@@ -392,6 +392,11 @@
     return QVector<qreal>({1});
 }
 
+QVector<int> Platform::screenRotations() const
+{
+    return {0};
+}
+
 bool Platform::requiresCompositing() const
 {
     return true;
diff --git a/platformsupport/scenes/opengl/abstract_egl_backend.h b/platformsupport/scenes/opengl/abstract_egl_backend.h
--- a/platformsupport/scenes/opengl/abstract_egl_backend.h
+++ b/platformsupport/scenes/opengl/abstract_egl_backend.h
@@ -38,6 +38,7 @@
 
 namespace KWin
 {
+class AbstractOutput;
 
 class KWIN_EXPORT AbstractEglBackend : public QObject, public OpenGLBackend
 {
@@ -77,6 +78,8 @@
 
     bool createContext();
 
+    static QRect orientateRect(AbstractOutput *output, const QRect &r);
+
 private:
     void unbindWaylandDisplay();
 
diff --git a/platformsupport/scenes/opengl/abstract_egl_backend.cpp b/platformsupport/scenes/opengl/abstract_egl_backend.cpp
--- a/platformsupport/scenes/opengl/abstract_egl_backend.cpp
+++ b/platformsupport/scenes/opengl/abstract_egl_backend.cpp
@@ -19,6 +19,7 @@
 *********************************************************************/
 #include "abstract_egl_backend.h"
 #include "texture.h"
+#include "abstract_output.h"
 #include "composite.h"
 #include "egl_context_attribute_builder.h"
 #include "options.h"
@@ -546,5 +547,16 @@
     return true;
 }
 
+
+QRect AbstractEglBackend::orientateRect(AbstractOutput *output, const QRect &r)
+{
+    if (output->softwareRotationAngle() != 0) {
+        QTransform m;
+        m.rotate(-output->softwareRotationAngle(), Qt::ZAxis);
+        return QRect(m.map(r.topLeft()), r.size());
+    }
+    return r;
+}
+
 }
 
diff --git a/plugins/platforms/drm/drm_output.h b/plugins/platforms/drm/drm_output.h
--- a/plugins/platforms/drm/drm_output.h
+++ b/plugins/platforms/drm/drm_output.h
@@ -87,6 +87,10 @@
 
     bool supportsTransformations() const;
 
+    int softwareRotationAngle() const override {
+        return m_softwareRotationAngle;
+    }
+
 Q_SIGNALS:
     void dpmsChanged();
 
@@ -160,6 +164,7 @@
     bool m_hasNewCursor = false;
     bool m_internal = false;
     bool m_deleted = false;
+    int m_softwareRotationAngle = 0;
 };
 
 }
diff --git a/plugins/platforms/drm/drm_output.cpp b/plugins/platforms/drm/drm_output.cpp
--- a/plugins/platforms/drm/drm_output.cpp
+++ b/plugins/platforms/drm/drm_output.cpp
@@ -24,6 +24,7 @@
 #include "drm_object_connector.h"
 
 #include <errno.h>
+#include <cmath>
 
 #include "composite.h"
 #include "logind.h"
@@ -713,6 +714,7 @@
     using KWayland::Server::OutputDeviceInterface;
     using KWayland::Server::OutputInterface;
     auto wlOutput = waylandOutput();
+    m_softwareRotationAngle = 0;
 
     switch (transform) {
     case OutputDeviceInterface::Transform::Normal:
@@ -804,7 +806,7 @@
 
 QSize DrmOutput::pixelSize() const
 {
-    return orientateSize(QSize(m_mode.hdisplay, m_mode.vdisplay));
+    return QSize(m_mode.hdisplay, m_mode.vdisplay);
 }
 
 void DrmOutput::setWaylandMode()
@@ -897,6 +899,27 @@
 
 }
 
+///Copied from QPlatformScreen
+static int angleBetween(Qt::ScreenOrientation a, Qt::ScreenOrientation b)
+{
+    if (a == Qt::PrimaryOrientation) a = Qt::LandscapeOrientation;
+    if (b == Qt::PrimaryOrientation) b = Qt::LandscapeOrientation;
+
+    if (a == b)
+        return 0;
+
+    int ia = std::log2(uint(a));
+    int ib = std::log2(uint(b));
+
+    int delta = ia - ib;
+
+    if (delta < 0)
+        delta = delta + 4;
+
+    int angles[] = { 0, 90, 180, 270 };
+    return angles[delta];
+}
+
 bool DrmOutput::presentAtomically(DrmBuffer *buffer)
 {
     if (!LogindIntegration::self()->isActiveSession()) {
@@ -919,7 +942,8 @@
         // go back to previous state
         if (m_lastWorkingState.valid) {
             m_mode = m_lastWorkingState.mode;
-            setOrientation(m_lastWorkingState.orientation);
+            m_softwareRotationAngle = angleBetween(m_lastWorkingState.orientation, orientation());
+            qCDebug(KWIN_DRM) << "software rotation to" << m_softwareRotationAngle;
             setGlobalPos(m_lastWorkingState.globalPos);
             if (m_primaryPlane) {
                 m_primaryPlane->setTransformation(m_lastWorkingState.planeTransformations);
diff --git a/plugins/platforms/drm/egl_gbm_backend.cpp b/plugins/platforms/drm/egl_gbm_backend.cpp
--- a/plugins/platforms/drm/egl_gbm_backend.cpp
+++ b/plugins/platforms/drm/egl_gbm_backend.cpp
@@ -215,9 +215,9 @@
     }
 }
 
-bool EglGbmBackend::makeContextCurrent(const Output &output)
+bool EglGbmBackend::makeContextCurrent(const Output &_output)
 {
-    const EGLSurface surface = output.eglSurface;
+    const EGLSurface surface = _output.eglSurface;
     if (surface == EGL_NO_SURFACE) {
         return false;
     }
@@ -231,15 +231,15 @@
         qCWarning(KWIN_DRM) << "Error occurred while creating context " << error;
         return false;
     }
-    // TODO: ensure the viewport is set correctly each time
-    const QSize &overall = screens()->size();
-    const QRect &v = output.output->geometry();
-    // TODO: are the values correct?
-
-    qreal scale = output.output->scale();
 
+    DrmOutput* output = _output.output;
+    const QRect v = orientateRect(output, output->geometry());
+    const qreal scale = output->scale();
+    const QSize overall = screens()->size();
+    const QSize orientedOverall = output->orientateSize(overall) * scale;
     glViewport(-v.x() * scale, (v.height() - overall.height() + v.y()) * scale,
-               overall.width() * scale, overall.height() * scale);
+               orientedOverall.width(), orientedOverall.height());
+
     return true;
 }
 
diff --git a/plugins/platforms/virtual/screens_virtual.h b/plugins/platforms/virtual/screens_virtual.h
--- a/plugins/platforms/virtual/screens_virtual.h
+++ b/plugins/platforms/virtual/screens_virtual.h
@@ -33,6 +33,9 @@
     VirtualScreens(VirtualBackend *backend, QObject *parent = nullptr);
     virtual ~VirtualScreens();
     void init() override;
+    int rotation(int /*screen*/) const override {
+        return 0;
+    }
 
 private:
     void createOutputs();
diff --git a/plugins/platforms/virtual/virtual_output.h b/plugins/platforms/virtual/virtual_output.h
--- a/plugins/platforms/virtual/virtual_output.h
+++ b/plugins/platforms/virtual/virtual_output.h
@@ -49,6 +49,10 @@
         return m_gammaResult;
     }
 
+    int softwareRotationAngle() const override {
+        return 0;
+    }
+
 private:
     Q_DISABLE_COPY(VirtualOutput);
     friend class VirtualBackend;
diff --git a/plugins/platforms/wayland/egl_wayland_backend.cpp b/plugins/platforms/wayland/egl_wayland_backend.cpp
--- a/plugins/platforms/wayland/egl_wayland_backend.cpp
+++ b/plugins/platforms/wayland/egl_wayland_backend.cpp
@@ -240,13 +240,13 @@
         return false;
     }
 
-    const QRect &v = output->m_waylandOutput->geometry();
-
-    qreal scale = output->m_waylandOutput->scale();
-
+    const QRect v = orientateRect(output->m_waylandOutput, output->m_waylandOutput->geometry());
+    const qreal scale = output->m_waylandOutput->scale();
     const QSize overall = screens()->size();
+    const QSize orientedOverall = output->m_waylandOutput->orientateSize(overall) * scale;
     glViewport(-v.x() * scale, (v.height() - overall.height() + v.y()) * scale,
-               overall.width() * scale, overall.height() * scale);
+               orientedOverall.width(), orientedOverall.height());
+
     return true;
 }
 
diff --git a/plugins/platforms/x11/standalone/screens_xrandr.h b/plugins/platforms/x11/standalone/screens_xrandr.h
--- a/plugins/platforms/x11/standalone/screens_xrandr.h
+++ b/plugins/platforms/x11/standalone/screens_xrandr.h
@@ -41,6 +41,9 @@
     float refreshRate(int screen) const override;
     QSize size(int screen) const override;
     QSize displaySize() const override;
+    int rotation(int /*screen*/) const override {
+        return 0;
+    }
 
     using QObject::event;
     bool event(xcb_generic_event_t *event) override;
diff --git a/plugins/scenes/opengl/scene_opengl.h b/plugins/scenes/opengl/scene_opengl.h
--- a/plugins/scenes/opengl/scene_opengl.h
+++ b/plugins/scenes/opengl/scene_opengl.h
@@ -94,7 +94,7 @@
     void handleGraphicsReset(GLenum status);
 
     virtual void doPaintBackground(const QVector<float> &vertices) = 0;
-    virtual void updateProjectionMatrix() = 0;
+    virtual void updateProjectionMatrix(int rotation) = 0;
 
 protected:
     bool init_ok;
@@ -128,12 +128,12 @@
     virtual void doPaintBackground(const QVector< float >& vertices);
     virtual Scene::Window *createWindow(Toplevel *t);
     virtual void finalDrawWindow(EffectWindowImpl* w, int mask, QRegion region, WindowPaintData& data);
-    virtual void updateProjectionMatrix() override;
+    virtual void updateProjectionMatrix(int rotation) override;
     void paintCursor() override;
 
 private:
     void performPaintWindow(EffectWindowImpl* w, int mask, QRegion region, WindowPaintData& data);
-    QMatrix4x4 createProjectionMatrix() const;
+    QMatrix4x4 createProjectionMatrix(int rotation) const;
 
 private:
     LanczosFilter *m_lanczosFilter;
diff --git a/plugins/scenes/opengl/scene_opengl.cpp b/plugins/scenes/opengl/scene_opengl.cpp
--- a/plugins/scenes/opengl/scene_opengl.cpp
+++ b/plugins/scenes/opengl/scene_opengl.cpp
@@ -658,6 +658,7 @@
         // trigger start render timer
         m_backend->prepareRenderingFrame();
         for (int i = 0; i < screens()->count(); ++i) {
+            const int rotation = screens()->rotation(i);
             const QRect &geo = screens()->geometry(i);
             QRegion update;
             QRegion valid;
@@ -675,7 +676,8 @@
             }
 
             int mask = 0;
-            updateProjectionMatrix();
+            updateProjectionMatrix(rotation);
+
             paintScreen(&mask, damage.intersected(geo), repaint, &update, &valid, projectionMatrix(), geo);   // call generic implementation
             paintCursor();
 
@@ -700,7 +702,7 @@
         GLRenderTarget::setVirtualScreenScale(1);
 
         int mask = 0;
-        updateProjectionMatrix();
+        updateProjectionMatrix(0);
         paintScreen(&mask, damage, repaint, &updateRegion, &validRegion, projectionMatrix());   // call generic implementation
 
         if (!GLPlatform::instance()->isGLES()) {
@@ -962,7 +964,7 @@
     }
 }
 
-QMatrix4x4 SceneOpenGL2::createProjectionMatrix() const
+QMatrix4x4 SceneOpenGL2::createProjectionMatrix(int rotation) const
 {
     // Create a perspective projection with a 60° field-of-view,
     // and an aspect ratio of 1.0.
@@ -978,6 +980,9 @@
 
     QMatrix4x4 projection;
     projection.frustum(xMin, xMax, yMin, yMax, zNear, zFar);
+    if (rotation != 0) {
+        projection.rotate(rotation, 0, 0, 1);
+    }
 
     // Create a second matrix that transforms screen coordinates
     // to world coordinates.
@@ -994,9 +999,9 @@
     return projection * matrix;
 }
 
-void SceneOpenGL2::updateProjectionMatrix()
+void SceneOpenGL2::updateProjectionMatrix(int rotation)
 {
-    m_projectionMatrix = createProjectionMatrix();
+    m_projectionMatrix = createProjectionMatrix(rotation);
 }
 
 void SceneOpenGL2::paintSimpleScreen(int mask, QRegion region)
diff --git a/screens.h b/screens.h
--- a/screens.h
+++ b/screens.h
@@ -157,6 +157,8 @@
         return m_orientationSensor;
     }
 
+    virtual int rotation(int screen) const = 0;
+
 public Q_SLOTS:
     void reconfigure();
 
@@ -230,11 +232,13 @@
     QSize size(int screen) const override;
     qreal scale(int screen) const override;
     void updateCount() override;
+    int rotation(int screen) const override;
 
 private:
     Platform *m_backend;
     QVector<QRect> m_geometries;
     QVector<qreal> m_scales;
+    QVector<int> m_rotations;
 };
 
 inline
diff --git a/screens.cpp b/screens.cpp
--- a/screens.cpp
+++ b/screens.cpp
@@ -289,8 +289,14 @@
     return 1;
 }
 
+int BasicScreens::rotation(int screen) const
+{
+    return m_rotations.value(screen, 0);
+}
+
 void BasicScreens::updateCount()
 {
+    m_rotations = m_backend->screenRotations();
     m_geometries = m_backend->screenGeometries();
     m_scales = m_backend->screenScales();
     setCount(m_geometries.count());