diff --git a/src/plugins/clangcodemodel/clangeditordocumentparser.cpp b/src/plugins/clangcodemodel/clangeditordocumentparser.cpp
index 129c0669a61..332eb5a5eab 100644
--- a/src/plugins/clangcodemodel/clangeditordocumentparser.cpp
+++ b/src/plugins/clangcodemodel/clangeditordocumentparser.cpp
@@ -36,10 +36,11 @@ ClangEditorDocumentParser::ClangEditorDocumentParser(const QString &filePath)
 }
 
 void ClangEditorDocumentParser::updateHelper(const QFutureInterface<void> &,
-                                             const CppTools::WorkingCopy &)
+                                             const CppTools::WorkingCopy &,
+                                             const ProjectExplorer::Project *activeProject)
 {
     State state_ = state();
-    state_.projectPart = determineProjectPart(filePath(), configuration(), state_);
+    state_.projectPart = determineProjectPart(filePath(), configuration(), state_, activeProject);
     setState(state_);
 }
 
diff --git a/src/plugins/clangcodemodel/clangeditordocumentparser.h b/src/plugins/clangcodemodel/clangeditordocumentparser.h
index 848e31f1259..fdc01694191 100644
--- a/src/plugins/clangcodemodel/clangeditordocumentparser.h
+++ b/src/plugins/clangcodemodel/clangeditordocumentparser.h
@@ -38,7 +38,8 @@ public:
 
 private:
     void updateHelper(const QFutureInterface<void> &future,
-                      const CppTools::WorkingCopy &) override;
+                      const CppTools::WorkingCopy &,
+                      const ProjectExplorer::Project *activeProject) override;
 };
 
 } // namespace ClangCodeModel
diff --git a/src/plugins/clangcodemodel/clangeditordocumentprocessor.cpp b/src/plugins/clangcodemodel/clangeditordocumentprocessor.cpp
index 6192232be0d..3afd5c7c6a2 100644
--- a/src/plugins/clangcodemodel/clangeditordocumentprocessor.cpp
+++ b/src/plugins/clangcodemodel/clangeditordocumentprocessor.cpp
@@ -46,6 +46,8 @@
 #include <cpptools/cppworkingcopy.h>
 #include <cpptools/editordocumenthandle.h>
 
+#include <projectexplorer/session.h>
+
 #include <texteditor/convenience.h>
 #include <texteditor/fontsettings.h>
 #include <texteditor/texteditor.h>
@@ -115,7 +117,12 @@ void ClangEditorDocumentProcessor::run()
     connect(&m_parserWatcher, &QFutureWatcher<void>::finished,
             this, &ClangEditorDocumentProcessor::onParserFinished);
     const CppTools::WorkingCopy workingCopy = CppTools::CppModelManager::instance()->workingCopy();
-    const QFuture<void> future = ::Utils::runAsync(&runParser, parser(), workingCopy);
+    const ProjectExplorer::Project *activeProject
+            = ProjectExplorer::SessionManager::startupProject();
+    const QFuture<void> future = ::Utils::runAsync(&runParser,
+                                                   parser(),
+                                                   workingCopy,
+                                                   activeProject);
     m_parserWatcher.setFuture(future);
 
     // Run builtin processor
diff --git a/src/plugins/cpptools/baseeditordocumentparser.cpp b/src/plugins/cpptools/baseeditordocumentparser.cpp
index ce44c312ff0..579d3096242 100644
--- a/src/plugins/cpptools/baseeditordocumentparser.cpp
+++ b/src/plugins/cpptools/baseeditordocumentparser.cpp
@@ -77,17 +77,19 @@ void BaseEditorDocumentParser::setConfiguration(const Configuration &configurati
     m_configuration = configuration;
 }
 
-void BaseEditorDocumentParser::update(const WorkingCopy &workingCopy)
+void BaseEditorDocumentParser::update(const WorkingCopy &workingCopy,
+                                      const ProjectExplorer::Project *activeProject)
 {
     QFutureInterface<void> dummy;
-    update(dummy, workingCopy);
+    update(dummy, workingCopy, activeProject);
 }
 
 void BaseEditorDocumentParser::update(const QFutureInterface<void> &future,
-                                      const WorkingCopy &workingCopy)
+                                      const WorkingCopy &workingCopy,
+                                      const ProjectExplorer::Project *activeProject)
 {
     QMutexLocker locker(&m_updateIsRunning);
-    updateHelper(future, workingCopy);
+    updateHelper(future, workingCopy, activeProject);
 }
 
 BaseEditorDocumentParser::State BaseEditorDocumentParser::state() const
@@ -117,9 +119,11 @@ BaseEditorDocumentParser::Ptr BaseEditorDocumentParser::get(const QString &fileP
     return BaseEditorDocumentParser::Ptr();
 }
 
-ProjectPart::Ptr BaseEditorDocumentParser::determineProjectPart(const QString &filePath,
-                                                                const Configuration &config,
-                                                                const State &state)
+ProjectPart::Ptr BaseEditorDocumentParser::determineProjectPart(
+        const QString &filePath,
+        const Configuration &config,
+        const State &state,
+        const ProjectExplorer::Project *activeProject)
 {
     Internal::ProjectPartChooser chooser;
     chooser.setFallbackProjectPart([](){
@@ -136,7 +140,8 @@ ProjectPart::Ptr BaseEditorDocumentParser::determineProjectPart(const QString &f
     return chooser.choose(filePath,
                           state.projectPart,
                           config.manuallySetProjectPart,
-                          config.stickToPreviousProjectPart);
+                          config.stickToPreviousProjectPart,
+                          activeProject);
 }
 
 } // namespace CppTools
diff --git a/src/plugins/cpptools/baseeditordocumentparser.h b/src/plugins/cpptools/baseeditordocumentparser.h
index 328fe421fdb..9f107d52129 100644
--- a/src/plugins/cpptools/baseeditordocumentparser.h
+++ b/src/plugins/cpptools/baseeditordocumentparser.h
@@ -33,6 +33,8 @@
 #include <QObject>
 #include <QMutex>
 
+namespace ProjectExplorer { class Project; }
+
 namespace CppTools {
 
 class CPPTOOLS_EXPORT BaseEditorDocumentParser : public QObject
@@ -58,8 +60,11 @@ public:
     Configuration configuration() const;
     void setConfiguration(const Configuration &configuration);
 
-    void update(const WorkingCopy &workingCopy);
-    void update(const QFutureInterface<void> &future, const WorkingCopy &workingCopy);
+    void update(const WorkingCopy &workingCopy,
+                const ProjectExplorer::Project *activeProject);
+    void update(const QFutureInterface<void> &future,
+                const WorkingCopy &workingCopy,
+                const ProjectExplorer::Project *activeProject);
 
     ProjectPart::Ptr projectPart() const;
 
@@ -73,13 +78,15 @@ protected:
 
     static ProjectPart::Ptr determineProjectPart(const QString &filePath,
                                                  const Configuration &config,
-                                                 const State &state);
+                                                 const State &state,
+                                                 const ProjectExplorer::Project *activeProject);
 
     mutable QMutex m_stateAndConfigurationMutex;
 
 private:
     virtual void updateHelper(const QFutureInterface<void> &future,
-                              const WorkingCopy &workingCopy) = 0;
+                              const WorkingCopy &workingCopy,
+                              const ProjectExplorer::Project *activeProject) = 0;
 
     const QString m_filePath;
     Configuration m_configuration;
diff --git a/src/plugins/cpptools/baseeditordocumentprocessor.cpp b/src/plugins/cpptools/baseeditordocumentprocessor.cpp
index 1ae7f11b98e..69432dd6e2d 100644
--- a/src/plugins/cpptools/baseeditordocumentprocessor.cpp
+++ b/src/plugins/cpptools/baseeditordocumentprocessor.cpp
@@ -73,7 +73,8 @@ void BaseEditorDocumentProcessor::editorDocumentTimerRestarted()
 
 void BaseEditorDocumentProcessor::runParser(QFutureInterface<void> &future,
                                             BaseEditorDocumentParser::Ptr parser,
-                                            const WorkingCopy workingCopy)
+                                            const WorkingCopy workingCopy,
+                                            const ProjectExplorer::Project *activeProject)
 {
     future.setProgressRange(0, 1);
     if (future.isCanceled()) {
@@ -81,7 +82,7 @@ void BaseEditorDocumentProcessor::runParser(QFutureInterface<void> &future,
         return;
     }
 
-    parser->update(future, workingCopy);
+    parser->update(future, workingCopy, activeProject);
     CppToolsBridge::finishedRefreshingSourceFiles({parser->filePath()});
 
     future.setProgressValue(1);
diff --git a/src/plugins/cpptools/baseeditordocumentprocessor.h b/src/plugins/cpptools/baseeditordocumentprocessor.h
index f40c09ae761..a37be4ddcb2 100644
--- a/src/plugins/cpptools/baseeditordocumentprocessor.h
+++ b/src/plugins/cpptools/baseeditordocumentprocessor.h
@@ -91,7 +91,8 @@ signals:
 protected:
     static void runParser(QFutureInterface<void> &future,
                           BaseEditorDocumentParser::Ptr parser,
-                          const CppTools::WorkingCopy workingCopy);
+                          const CppTools::WorkingCopy workingCopy,
+                          const ProjectExplorer::Project *activeProject);
 
     // Convenience
     QString filePath() const { return m_filePath; }
diff --git a/src/plugins/cpptools/builtineditordocumentparser.cpp b/src/plugins/cpptools/builtineditordocumentparser.cpp
index 0258a537099..354951d9b67 100644
--- a/src/plugins/cpptools/builtineditordocumentparser.cpp
+++ b/src/plugins/cpptools/builtineditordocumentparser.cpp
@@ -56,7 +56,8 @@ BuiltinEditorDocumentParser::BuiltinEditorDocumentParser(const QString &filePath
 }
 
 void BuiltinEditorDocumentParser::updateHelper(const QFutureInterface<void> &future,
-                                               const WorkingCopy &theWorkingCopy)
+                                               const WorkingCopy &theWorkingCopy,
+                                               const ProjectExplorer::Project *activeProject)
 {
     if (filePath().isEmpty())
         return;
@@ -77,7 +78,7 @@ void BuiltinEditorDocumentParser::updateHelper(const QFutureInterface<void> &fut
     QString projectConfigFile;
     LanguageFeatures features = LanguageFeatures::defaultFeatures();
 
-    baseState.projectPart = determineProjectPart(filePath(), baseConfig, baseState);
+    baseState.projectPart = determineProjectPart(filePath(), baseConfig, baseState, activeProject);
 
     if (state.forceSnapshotInvalidation) {
         invalidateSnapshot = true;
diff --git a/src/plugins/cpptools/builtineditordocumentparser.h b/src/plugins/cpptools/builtineditordocumentparser.h
index 94ae556574c..463acd8026f 100644
--- a/src/plugins/cpptools/builtineditordocumentparser.h
+++ b/src/plugins/cpptools/builtineditordocumentparser.h
@@ -59,7 +59,8 @@ public:
 
 private:
     void updateHelper(const QFutureInterface<void> &future,
-                      const WorkingCopy &workingCopy) override;
+                      const WorkingCopy &workingCopy,
+                      const ProjectExplorer::Project *activeProject) override;
     void addFileAndDependencies(CPlusPlus::Snapshot *snapshot,
                                 QSet<Utils::FileName> *toRemove,
                                 const Utils::FileName &fileName) const;
diff --git a/src/plugins/cpptools/builtineditordocumentprocessor.cpp b/src/plugins/cpptools/builtineditordocumentprocessor.cpp
index 284e1af8ae9..1d7dbbb817f 100644
--- a/src/plugins/cpptools/builtineditordocumentprocessor.cpp
+++ b/src/plugins/cpptools/builtineditordocumentprocessor.cpp
@@ -32,6 +32,8 @@
 #include "cpptoolsreuse.h"
 #include "cppworkingcopy.h"
 
+#include <projectexplorer/session.h>
+
 #include <texteditor/convenience.h>
 #include <texteditor/fontsettings.h>
 #include <texteditor/refactoroverlay.h>
@@ -205,10 +207,13 @@ BuiltinEditorDocumentProcessor::~BuiltinEditorDocumentProcessor()
 void BuiltinEditorDocumentProcessor::run()
 {
     CppModelManager *mgr = CppModelManager::instance();
+    const ProjectExplorer::Project *activeProject
+            = ProjectExplorer::SessionManager::startupProject();
     m_parserFuture = Utils::runAsync(mgr->sharedThreadPool(),
                                      runParser,
                                      parser(),
-                                     mgr->workingCopy());
+                                     mgr->workingCopy(),
+                                     activeProject);
 }
 
 BaseEditorDocumentParser::Ptr BuiltinEditorDocumentProcessor::parser()
diff --git a/src/plugins/cpptools/builtinindexingsupport.cpp b/src/plugins/cpptools/builtinindexingsupport.cpp
index 2325ae138ea..5591a25aada 100644
--- a/src/plugins/cpptools/builtinindexingsupport.cpp
+++ b/src/plugins/cpptools/builtinindexingsupport.cpp
@@ -158,7 +158,7 @@ void indexFindErrors(QFutureInterface<void> &future, const ParseParams params)
         // Parse the file as precisely as possible
         BuiltinEditorDocumentParser parser(file);
         parser.setReleaseSourceAndAST(false);
-        parser.update(CppModelManager::instance()->workingCopy());
+        parser.update(CppModelManager::instance()->workingCopy(), nullptr);
         CPlusPlus::Document::Ptr document = parser.document();
         QTC_ASSERT(document, return);
 
diff --git a/src/plugins/cpptools/cppcompletionassist.cpp b/src/plugins/cpptools/cppcompletionassist.cpp
index 9aa5a4538f3..6b2c8c1b9a6 100644
--- a/src/plugins/cpptools/cppcompletionassist.cpp
+++ b/src/plugins/cpptools/cppcompletionassist.cpp
@@ -430,8 +430,7 @@ IAssistProcessor *InternalCompletionAssistProvider::createProcessor() const
     return new InternalCppCompletionAssistProcessor;
 }
 
-AssistInterface *InternalCompletionAssistProvider::createAssistInterface(
-        const QString &filePath,
+AssistInterface *InternalCompletionAssistProvider::createAssistInterface(const QString &filePath,
         const TextEditorWidget *textEditorWidget,
         const LanguageFeatures &languageFeatures,
         int position,
@@ -2123,7 +2122,7 @@ void CppCompletionAssistInterface::getCppSpecifics() const
     m_gotCppSpecifics = true;
 
     if (m_parser) {
-        m_parser->update(CppTools::CppModelManager::instance()->workingCopy());
+        m_parser->update(CppTools::CppModelManager::instance()->workingCopy(), nullptr);
         m_snapshot = m_parser->snapshot();
         m_headerPaths = m_parser->headerPaths();
     }
diff --git a/src/plugins/cpptools/cppmodelmanager_test.cpp b/src/plugins/cpptools/cppmodelmanager_test.cpp
index 622344218dc..69d2087716e 100644
--- a/src/plugins/cpptools/cppmodelmanager_test.cpp
+++ b/src/plugins/cpptools/cppmodelmanager_test.cpp
@@ -877,7 +877,7 @@ void CppToolsPlugin::test_modelmanager_precompiled_headers()
         BaseEditorDocumentParser::Configuration config = parser->configuration();
         config.usePrecompiledHeaders = true;
         parser->setConfiguration(config);
-        parser->update(CppModelManager::instance()->workingCopy());
+        parser->update(CppModelManager::instance()->workingCopy(), nullptr);
 
         // Check if defines from pch are considered
         Document::Ptr document = mm->document(fileName);
@@ -955,7 +955,7 @@ void CppToolsPlugin::test_modelmanager_defines_per_editor()
         BaseEditorDocumentParser::Configuration config = parser->configuration();
         config.editorDefines = editorDefines.toUtf8();
         parser->setConfiguration(config);
-        parser->update(CppModelManager::instance()->workingCopy());
+        parser->update(CppModelManager::instance()->workingCopy(), nullptr);
 
         Document::Ptr doc = mm->document(main1File);
         QCOMPARE(nameOfFirstDeclaration(doc), firstDeclarationName);
diff --git a/src/plugins/cpptools/cppprojectpartchooser.cpp b/src/plugins/cpptools/cppprojectpartchooser.cpp
index 19074ff1845..0fb20f4750c 100644
--- a/src/plugins/cpptools/cppprojectpartchooser.cpp
+++ b/src/plugins/cpptools/cppprojectpartchooser.cpp
@@ -25,15 +25,25 @@
 
 #include "cppprojectpartchooser.h"
 
+#include <utils/algorithm.h>
 #include <utils/qtcassert.h>
 
 namespace CppTools {
 namespace Internal {
 
+static ProjectPart::Ptr selectFromActiveProject(const QList<ProjectPart::Ptr> &projectParts,
+                                                const ProjectExplorer::Project *activeProject)
+{
+    return Utils::findOr(projectParts, projectParts.first(), [&](const ProjectPart::Ptr &projectPart){
+        return projectPart->project == activeProject;
+    });
+}
+
 ProjectPart::Ptr ProjectPartChooser::choose(const QString &filePath,
                                             const ProjectPart::Ptr &currentProjectPart,
                                             const ProjectPart::Ptr &manuallySetProjectPart,
-                                            bool stickToPreviousProjectPart) const
+                                            bool stickToPreviousProjectPart,
+                                            const ProjectExplorer::Project *activeProject) const
 {
     QTC_CHECK(m_projectPartsForFile);
     QTC_CHECK(m_projectPartsFromDependenciesForFile);
@@ -57,11 +67,11 @@ ProjectPart::Ptr ProjectPartChooser::choose(const QString &filePath,
             // Fall-back step 2: Use fall-back part from the model manager:
             projectPart = m_fallbackProjectPart();
         else
-            projectPart = projectParts.first();
+            projectPart = selectFromActiveProject(projectParts, activeProject);
     } else {
         if (!projectParts.contains(projectPart))
             // Apparently the project file changed, so update our project part.
-            projectPart = projectParts.first();
+            projectPart = selectFromActiveProject(projectParts, activeProject);
     }
 
     return projectPart;
diff --git a/src/plugins/cpptools/cppprojectpartchooser.h b/src/plugins/cpptools/cppprojectpartchooser.h
index 0b9095bfdaa..fb26c3270d5 100644
--- a/src/plugins/cpptools/cppprojectpartchooser.h
+++ b/src/plugins/cpptools/cppprojectpartchooser.h
@@ -29,6 +29,8 @@
 
 #include <functional>
 
+namespace ProjectExplorer { class Project; }
+
 namespace CppTools {
 namespace Internal {
 
@@ -48,7 +50,8 @@ public:
     ProjectPart::Ptr choose(const QString &filePath,
                             const ProjectPart::Ptr &currentProjectPart,
                             const ProjectPart::Ptr &manuallySetProjectPart,
-                            bool stickToPreviousProjectPart) const;
+                            bool stickToPreviousProjectPart,
+                            const ProjectExplorer::Project *activeProject) const;
 
 private:
     FallBackProjectPart m_fallbackProjectPart;
diff --git a/tests/unit/unittest/cppprojectpartchooser-test.cpp b/tests/unit/unittest/cppprojectpartchooser-test.cpp
index 2a6e85946de..528f773c3ac 100644
--- a/tests/unit/unittest/cppprojectpartchooser-test.cpp
+++ b/tests/unit/unittest/cppprojectpartchooser-test.cpp
@@ -41,11 +41,14 @@ protected:
     void SetUp() override;
     const ProjectPart::Ptr choose() const;
 
+    static QList<ProjectPart::Ptr> createProjectPartsWithDifferentProjects();
+
 protected:
     QString filePath;
     ProjectPart::Ptr currentProjectPart{new ProjectPart};
     ProjectPart::Ptr manuallySetProjectPart;
     bool stickToPreviousProjectPart = false;
+    const ProjectExplorer::Project *activeProject = nullptr;
     ::ProjectPartChooser chooser;
 
     QList<ProjectPart::Ptr> projectPartsForFile;
@@ -73,6 +76,30 @@ TEST_F(ProjectPartChooser, ForMultipleChoosePrevious)
     ASSERT_THAT(chosen, Eq(currentProjectPart));
 }
 
+TEST_F(ProjectPartChooser, ForMultipleChooseFromActiveProject)
+{
+    const QList<ProjectPart::Ptr> projectParts = createProjectPartsWithDifferentProjects();
+    const ProjectPart::Ptr secondProjectPart = projectParts.at(1);
+    projectPartsForFile += projectParts;
+    activeProject = secondProjectPart->project;
+
+    const ProjectPart::Ptr chosen = choose();
+
+    ASSERT_THAT(chosen, Eq(secondProjectPart));
+}
+
+TEST_F(ProjectPartChooser, ForMultipleFromDependenciesChooseFromActiveProject)
+{
+    const QList<ProjectPart::Ptr> projectParts = createProjectPartsWithDifferentProjects();
+    const ProjectPart::Ptr secondProjectPart = projectParts.at(1);
+    projectPartsFromDependenciesForFile += projectParts;
+    activeProject = secondProjectPart->project;
+
+    const ProjectPart::Ptr chosen = choose();
+
+    ASSERT_THAT(chosen, Eq(secondProjectPart));
+}
+
 TEST_F(ProjectPartChooser, IfProjectIsGoneStickToPrevious) // Built-in Code Model
 {
     stickToPreviousProjectPart = true;
@@ -94,7 +121,7 @@ TEST_F(ProjectPartChooser, IfProjectIsGoneDoNotStickToPrevious) // Clang Code Mo
 
 TEST_F(ProjectPartChooser, ForMultipleChooseNewIfPreviousIsGone)
 {
-    const ProjectPart::Ptr newProjectPart;
+    const ProjectPart::Ptr newProjectPart{new ProjectPart};
     projectPartsForFile += newProjectPart;
 
     const ProjectPart::Ptr chosen = choose();
@@ -139,7 +166,22 @@ const ProjectPart::Ptr ProjectPartChooser::choose() const
     return chooser.choose(filePath,
                           currentProjectPart,
                           manuallySetProjectPart,
-                          stickToPreviousProjectPart);
+                          stickToPreviousProjectPart,
+                          activeProject);
+}
+
+QList<ProjectPart::Ptr> ProjectPartChooser::createProjectPartsWithDifferentProjects()
+{
+    QList<ProjectPart::Ptr> projectParts;
+
+    const ProjectPart::Ptr p1{new ProjectPart};
+    p1->project = reinterpret_cast<ProjectExplorer::Project *>(1 << 0);
+    projectParts.append(p1);
+    const ProjectPart::Ptr p2{new ProjectPart};
+    p2->project = reinterpret_cast<ProjectExplorer::Project *>(1 << 1);
+    projectParts.append(p2);
+
+    return projectParts;
 }
 
 } // anonymous namespace