diff --git a/kdevplatform/project/interfaces/ibuildsystemmanager.h b/kdevplatform/project/interfaces/ibuildsystemmanager.h
--- a/kdevplatform/project/interfaces/ibuildsystemmanager.h
+++ b/kdevplatform/project/interfaces/ibuildsystemmanager.h
@@ -125,6 +125,11 @@
      * Get the toplevel build directory for the project
      */
     virtual Path buildDirectory(ProjectBaseItem*) const = 0;
+
+    /**
+     * @returns the extra arguments that will be passed to the compiler when building @p item
+     */
+    virtual QString extraArguments(ProjectBaseItem* item) const = 0;
 };
 
 }
diff --git a/languages/plugins/custom-definesandincludes/definesandincludesmanager.cpp b/languages/plugins/custom-definesandincludes/definesandincludesmanager.cpp
--- a/languages/plugins/custom-definesandincludes/definesandincludesmanager.cpp
+++ b/languages/plugins/custom-definesandincludes/definesandincludesmanager.cpp
@@ -356,6 +356,11 @@
 
     Q_ASSERT(QThread::currentThread() == qApp->thread());
 
+    auto buildManager = item->project()->buildSystemManager();
+    if ( buildManager ) {
+        return buildManager->extraArguments(item);
+    }
+
     auto cfg = item->project()->projectConfiguration().data();
     const auto arguments = findConfigForItem(m_settings->readPaths(cfg), item).parserArguments;
     return argumentsForPath(item->path(), arguments);
diff --git a/projectmanagers/cmake/cmakemanager.h b/projectmanagers/cmake/cmakemanager.h
--- a/projectmanagers/cmake/cmakemanager.h
+++ b/projectmanagers/cmake/cmakemanager.h
@@ -84,6 +84,7 @@
     KDevelop::Path::List includeDirectories(KDevelop::ProjectBaseItem *) const override;
     KDevelop::Path::List frameworkDirectories(KDevelop::ProjectBaseItem *item) const override;
     QHash<QString, QString> defines(KDevelop::ProjectBaseItem *) const override;
+    QString extraArguments(KDevelop::ProjectBaseItem * item) const override;
 
     KDevelop::ProjectTargetItem* createTarget( const QString&, KDevelop::ProjectFolderItem* ) override { return nullptr; }
 
diff --git a/projectmanagers/cmake/cmakemanager.cpp b/projectmanagers/cmake/cmakemanager.cpp
--- a/projectmanagers/cmake/cmakemanager.cpp
+++ b/projectmanagers/cmake/cmakemanager.cpp
@@ -286,6 +286,11 @@
     return fileInformation(item).defines;
 }
 
+QString CMakeManager::extraArguments(KDevelop::ProjectBaseItem* item) const
+{
+    return fileInformation(item).compileFlags;
+}
+
 KDevelop::IProjectBuilder * CMakeManager::builder() const
 {
     IPlugin* i = core()->pluginController()->pluginForExtension( QStringLiteral("org.kdevelop.IProjectBuilder"), QStringLiteral("KDevCMakeBuilder"));
diff --git a/projectmanagers/cmake/cmakeprojectdata.h b/projectmanagers/cmake/cmakeprojectdata.h
--- a/projectmanagers/cmake/cmakeprojectdata.h
+++ b/projectmanagers/cmake/cmakeprojectdata.h
@@ -39,6 +39,7 @@
 {
     KDevelop::Path::List includes;
     KDevelop::Path::List frameworkDirectories;
+    QString compileFlags;
     QHash<QString, QString> defines;
 };
 inline QDebug &operator<<(QDebug debug, const CMakeFile& file)
diff --git a/projectmanagers/cmake/cmakeserverimportjob.cpp b/projectmanagers/cmake/cmakeserverimportjob.cpp
--- a/projectmanagers/cmake/cmakeserverimportjob.cpp
+++ b/projectmanagers/cmake/cmakeserverimportjob.cpp
@@ -119,7 +119,9 @@
                     const auto fileGroup = fileGroupValue.toObject();
                     CMakeFile file;
                     file.includes = kTransform<KDevelop::Path::List>(fileGroup.value(QStringLiteral("includePath")).toArray(), [](const QJsonValue& val) { return KDevelop::Path(val.toObject().value(QStringLiteral("path")).toString()); });
-                    file.defines = processDefines(fileGroup.value(QStringLiteral("compileFlags")).toString(), fileGroup.value(QStringLiteral("defines")).toArray());
+
+                    file.compileFlags = fileGroup.value(QStringLiteral("compileFlags")).toString();
+                    file.defines = processDefines(file.compileFlags, fileGroup.value(QStringLiteral("defines")).toArray());
 
                     const auto sourcesArray = fileGroup.value(QStringLiteral("sources")).toArray();
                     const KDevelop::Path::List sources = kTransform<KDevelop::Path::List>(sourcesArray, [targetDir](const QJsonValue& val) { return KDevelop::Path(targetDir, val.toString()); });
diff --git a/projectmanagers/custom-buildsystem/custombuildsystemplugin.h b/projectmanagers/custom-buildsystem/custombuildsystemplugin.h
--- a/projectmanagers/custom-buildsystem/custombuildsystemplugin.h
+++ b/projectmanagers/custom-buildsystem/custombuildsystemplugin.h
@@ -76,6 +76,7 @@
     QHash<QString, QString> defines( KDevelop::ProjectBaseItem* ) const override;
     KDevelop::Path::List includeDirectories( KDevelop::ProjectBaseItem* ) const override;
     KDevelop::Path::List frameworkDirectories( KDevelop::ProjectBaseItem* ) const override;
+    QString extraArguments(KDevelop::ProjectBaseItem * item) const override;
     bool removeFilesFromTargets( const QList<KDevelop::ProjectFileItem*>& ) override;
     bool removeTarget( KDevelop::ProjectTargetItem* target ) override;
     QList<KDevelop::ProjectTargetItem*> targets( KDevelop::ProjectFolderItem* ) const override;
diff --git a/projectmanagers/custom-buildsystem/custombuildsystemplugin.cpp b/projectmanagers/custom-buildsystem/custombuildsystemplugin.cpp
--- a/projectmanagers/custom-buildsystem/custombuildsystemplugin.cpp
+++ b/projectmanagers/custom-buildsystem/custombuildsystemplugin.cpp
@@ -141,6 +141,11 @@
     return {};
 }
 
+QString CustomBuildSystem::extraArguments(KDevelop::ProjectBaseItem*) const
+{
+    return {};
+}
+
 KJob* CustomBuildSystem::install( KDevelop::ProjectBaseItem* item, const QUrl &installPrefix )
 {
     auto job = new CustomBuildJob( this, item, CustomBuildSystemTool::Install );
diff --git a/projectmanagers/custommake/custommakemanager.h b/projectmanagers/custommake/custommakemanager.h
--- a/projectmanagers/custommake/custommakemanager.h
+++ b/projectmanagers/custommake/custommakemanager.h
@@ -56,6 +56,8 @@
      */
     QHash<QString,QString> defines(KDevelop::ProjectBaseItem*) const override;
 
+    QString extraArguments(KDevelop::ProjectBaseItem * item) const override;
+
     /**
      * Create a new target
      *
diff --git a/projectmanagers/custommake/custommakemanager.cpp b/projectmanagers/custommake/custommakemanager.cpp
--- a/projectmanagers/custommake/custommakemanager.cpp
+++ b/projectmanagers/custommake/custommakemanager.cpp
@@ -151,6 +151,11 @@
     return QHash<QString,QString>();
 }
 
+QString CustomMakeManager::extraArguments(KDevelop::ProjectBaseItem*) const
+{
+    return {};
+}
+
 ProjectTargetItem* CustomMakeManager::createTarget(const QString& target, KDevelop::ProjectFolderItem *parent)
 {
     Q_UNUSED(target)
diff --git a/projectmanagers/qmake/qmakemanager.h b/projectmanagers/qmake/qmakemanager.h
--- a/projectmanagers/qmake/qmakemanager.h
+++ b/projectmanagers/qmake/qmakemanager.h
@@ -60,6 +60,7 @@
     KDevelop::Path::List includeDirectories(KDevelop::ProjectBaseItem*) const override;
     KDevelop::Path::List frameworkDirectories(KDevelop::ProjectBaseItem* item) const override;
     QHash<QString,QString> defines(KDevelop::ProjectBaseItem*) const override;
+    QString extraArguments(KDevelop::ProjectBaseItem * item) const override;
     bool hasBuildInfo(KDevelop::ProjectBaseItem*) const override;
 
     KDevelop::ProjectTargetItem* createTarget( const QString&, KDevelop::ProjectFolderItem* ) override
diff --git a/projectmanagers/qmake/qmakemanager.cpp b/projectmanagers/qmake/qmakemanager.cpp
--- a/projectmanagers/qmake/qmakemanager.cpp
+++ b/projectmanagers/qmake/qmakemanager.cpp
@@ -448,6 +448,21 @@
     return d;
 }
 
+QString QMakeProjectManager::extraArguments(KDevelop::ProjectBaseItem* item) const
+{
+    QMakeFolderItem* folder = findQMakeFolderParent(item);
+    if (!folder) {
+        // happens for bad qmake configurations
+        return {};
+    }
+
+    QStringList d;
+    foreach (QMakeProjectFile* pro, folder->projectFiles()) {
+        d << pro->extraArguments();
+    }
+    return d.join(QLatin1Char(' '));
+}
+
 bool QMakeProjectManager::hasBuildInfo(KDevelop::ProjectBaseItem* item) const
 {
     return findQMakeFolderParent(item);
diff --git a/projectmanagers/qmake/qmakeprojectfile.h b/projectmanagers/qmake/qmakeprojectfile.h
--- a/projectmanagers/qmake/qmakeprojectfile.h
+++ b/projectmanagers/qmake/qmakeprojectfile.h
@@ -52,6 +52,7 @@
     QStringList filesForTarget( const QString& ) const;
     QStringList includeDirectories() const;
     QStringList frameworkDirectories() const;
+    QStringList extraArguments() const;
 
     QStringList targets() const;
 
diff --git a/projectmanagers/qmake/qmakeprojectfile.cpp b/projectmanagers/qmake/qmakeprojectfile.cpp
--- a/projectmanagers/qmake/qmakeprojectfile.cpp
+++ b/projectmanagers/qmake/qmakeprojectfile.cpp
@@ -287,6 +287,25 @@
     return fwDirs;
 }
 
+QStringList QMakeProjectFile::extraArguments() const
+{
+    const auto variablesToCheck = {QStringLiteral("QMAKE_CFLAGS"),
+                                QStringLiteral("QMAKE_CXXFLAGS"),
+                                QStringLiteral("QMAKE_LFLAGS")};
+    const QVector<QLatin1String> prefixes = { QLatin1String("-F"), QLatin1String("-iframework"), QLatin1String("-I") };
+    QStringList args;
+    foreach (const auto& var, variablesToCheck) {
+        foreach (const auto& arg, variableValues(var)) {
+            for (const auto& prefix: prefixes) {
+                if (arg.startsWith(prefix)) {
+                    args << arg;
+                }
+            }
+        }
+    }
+    return args;
+}
+
 QStringList QMakeProjectFile::files() const
 {
     ifDebug(qCDebug(KDEV_QMAKE) << "Fetching files";)