diff --git a/src/tools/clangbackend/source/clangcodemodelserver.cpp b/src/tools/clangbackend/source/clangcodemodelserver.cpp
index d3e873d7323..7e004e17d03 100644
--- a/src/tools/clangbackend/source/clangcodemodelserver.cpp
+++ b/src/tools/clangbackend/source/clangcodemodelserver.cpp
@@ -28,7 +28,6 @@
 #include "clangdocuments.h"
 #include "clangdocumentsuspenderresumer.h"
 #include "clangfilesystemwatcher.h"
-#include "clangtranslationunits.h"
 #include "codecompleter.h"
 #include "diagnosticset.h"
 #include "tokeninfos.h"
@@ -158,12 +157,17 @@ void ClangCodeModelServer::registerProjectPartsForEditor(const RegisterProjectPa
         std::vector<Document> affectedDocuments = documents.setDocumentsDirtyIfProjectPartChanged();
 
         for (Document &document : affectedDocuments) {
-            document.setResponsivenessIncreaseNeeded(document.isResponsivenessIncreased());
+            documents.remove({document.fileContainer()});
 
-            documentProcessors().remove(document);
-            document.translationUnits().removeAll();
-            document.translationUnits().createAndAppend();
-            documentProcessors().create(document);
+            Document newDocument = *documents.create({document.fileContainer()}).begin();
+            newDocument.setDirtyIfDependencyIsMet(document.filePath());
+            newDocument.setIsUsedByCurrentEditor(document.isUsedByCurrentEditor());
+            newDocument.setIsVisibleInEditor(document.isVisibleInEditor(), document.visibleTimePoint());
+            newDocument.setResponsivenessIncreaseNeeded(document.isResponsivenessIncreased());
+
+            documentProcessors().reset(document, newDocument);
+
+            QTC_CHECK(document.useCount() == 1);
         }
 
         processJobsForDirtyAndVisibleDocuments();
diff --git a/src/tools/clangbackend/source/clangdocument.cpp b/src/tools/clangbackend/source/clangdocument.cpp
index cbbaf51b332..bef88e9cb28 100644
--- a/src/tools/clangbackend/source/clangdocument.cpp
+++ b/src/tools/clangbackend/source/clangdocument.cpp
@@ -155,6 +155,11 @@ bool Document::isParsed() const
     return d->translationUnits.areAllTranslationUnitsParsed();
 }
 
+long Document::useCount() const
+{
+    return d.use_count();
+}
+
 Utf8String Document::filePath() const
 {
     checkIfNull();
@@ -175,6 +180,7 @@ FileContainer Document::fileContainer() const
 
     return FileContainer(d->filePath,
                          d->projectPart.id(),
+                         d->fileArguments,
                          Utf8String(),
                          false,
                          d->documentRevision);
diff --git a/src/tools/clangbackend/source/clangdocument.h b/src/tools/clangbackend/source/clangdocument.h
index 415deefbe9d..92a852c820a 100644
--- a/src/tools/clangbackend/source/clangdocument.h
+++ b/src/tools/clangbackend/source/clangdocument.h
@@ -78,6 +78,7 @@ public:
     bool isNull() const;
     bool isIntact() const;
     bool isParsed() const;
+    long useCount() const;
 
     Utf8String filePath() const;
     Utf8StringVector fileArguments() const;
diff --git a/src/tools/clangbackend/source/clangdocumentprocessor.cpp b/src/tools/clangbackend/source/clangdocumentprocessor.cpp
index 8196e804d0f..3c51db5b499 100644
--- a/src/tools/clangbackend/source/clangdocumentprocessor.cpp
+++ b/src/tools/clangbackend/source/clangdocumentprocessor.cpp
@@ -102,6 +102,12 @@ JobRequests DocumentProcessor::process()
     return d->jobs.process();
 }
 
+JobRequests DocumentProcessor::stop()
+{
+    d->supportiveTranslationUnitInitializer.abort();
+    return d->jobs.stop();
+}
+
 Document DocumentProcessor::document() const
 {
     return d->document;
diff --git a/src/tools/clangbackend/source/clangdocumentprocessor.h b/src/tools/clangbackend/source/clangdocumentprocessor.h
index 9c3fb147f94..8f4e8051586 100644
--- a/src/tools/clangbackend/source/clangdocumentprocessor.h
+++ b/src/tools/clangbackend/source/clangdocumentprocessor.h
@@ -59,6 +59,7 @@ public:
                         = PreferredTranslationUnit::RecentlyParsed);
 
     JobRequests process();
+    JobRequests stop();
 
     Document document() const;
 
diff --git a/src/tools/clangbackend/source/clangdocumentprocessors.cpp b/src/tools/clangbackend/source/clangdocumentprocessors.cpp
index 611611a41f5..ef17dddee0e 100644
--- a/src/tools/clangbackend/source/clangdocumentprocessors.cpp
+++ b/src/tools/clangbackend/source/clangdocumentprocessors.cpp
@@ -28,6 +28,8 @@
 #include "clangexceptions.h"
 #include "projectpart.h"
 
+#include <utils/algorithm.h>
+
 namespace ClangBackEnd {
 
 DocumentProcessors::DocumentProcessors(Documents &documents,
@@ -84,6 +86,25 @@ void DocumentProcessors::remove(const Document &document)
         throw DocumentProcessorDoesNotExist(document.filePath(), document.projectPart().id());
 }
 
+void DocumentProcessors::reset(const Document &oldDocument, const Document &newDocument)
+{
+    // Wait until the currently running jobs finish and remember the not yet
+    // processed job requests for the new processor...
+    JobRequests jobsToTakeOver = processor(oldDocument).stop();
+    // ...but do not take over irrelevant ones.
+    jobsToTakeOver = Utils::filtered(jobsToTakeOver, [](const JobRequest &job){
+        return job.isTakeOverable();
+    });
+
+    // Remove current processor
+    remove(oldDocument);
+
+    // Create new processor and take over not yet processed jobs.
+    DocumentProcessor newProcessor = create(newDocument);
+    for (const JobRequest &job : jobsToTakeOver)
+        newProcessor.addJob(job);
+}
+
 JobRequests DocumentProcessors::process()
 {
     JobRequests jobsStarted;
diff --git a/src/tools/clangbackend/source/clangdocumentprocessors.h b/src/tools/clangbackend/source/clangdocumentprocessors.h
index 83e37f52766..4060fd4b47a 100644
--- a/src/tools/clangbackend/source/clangdocumentprocessors.h
+++ b/src/tools/clangbackend/source/clangdocumentprocessors.h
@@ -54,6 +54,7 @@ public:
     DocumentProcessor create(const Document &document);
     DocumentProcessor processor(const Document &document);
     void remove(const Document &document);
+    void reset(const Document &oldDocument, const Document &newDocument);
 
     JobRequests process();
 
diff --git a/src/tools/clangbackend/source/clangjobrequest.cpp b/src/tools/clangbackend/source/clangjobrequest.cpp
index e2c6f8f6d49..2715ecde1c7 100644
--- a/src/tools/clangbackend/source/clangjobrequest.cpp
+++ b/src/tools/clangbackend/source/clangjobrequest.cpp
@@ -168,6 +168,42 @@ static JobRequest::RunConditions conditionsForType(JobRequest::Type type)
     return conditions;
 }
 
+bool JobRequest::isTakeOverable() const
+{
+    // When new project information comes in and there are unprocessed jobs
+    // in the queue, we need to decide what to do with them.
+
+    switch (type) {
+    // Never discard these as the client side might wait for a response.
+    case Type::CompleteCode:
+    case Type::RequestReferences:
+    case Type::FollowSymbol:
+        return true;
+
+    // Discard this one as UpdateDocumentAnnotations will have the same effect.
+    case Type::RequestDocumentAnnotations:
+
+    // Discard Suspend because the document will be cleared anyway.
+    // Discard Resume because a (re)parse will happen on demand.
+    case Type::SuspendDocument:
+    case Type::ResumeDocument:
+
+    // Discard these as they are initial jobs that will be recreated on demand
+    // anyway.
+    case Type::UpdateDocumentAnnotations:
+    case Type::CreateInitialDocumentPreamble:
+
+    // Discard these as they only make sense in a row. Avoid splitting them up.
+    case Type::ParseSupportiveTranslationUnit:
+    case Type::ReparseSupportiveTranslationUnit:
+
+    case Type::Invalid:
+        return false;
+    }
+
+    return false;
+}
+
 JobRequest::JobRequest(Type type)
 {
     static quint64 idCounter = 0;
diff --git a/src/tools/clangbackend/source/clangjobrequest.h b/src/tools/clangbackend/source/clangjobrequest.h
index 81c78ba9dbc..04474967537 100644
--- a/src/tools/clangbackend/source/clangjobrequest.h
+++ b/src/tools/clangbackend/source/clangjobrequest.h
@@ -96,6 +96,7 @@ public:
 
     IAsyncJob *createJob() const;
     void cancelJob(ClangCodeModelClientInterface &client) const;
+    bool isTakeOverable() const;
 
     bool operator==(const JobRequest &other) const;
 
diff --git a/src/tools/clangbackend/source/clangjobs.cpp b/src/tools/clangbackend/source/clangjobs.cpp
index 872aecd936b..61f99b39852 100644
--- a/src/tools/clangbackend/source/clangjobs.cpp
+++ b/src/tools/clangbackend/source/clangjobs.cpp
@@ -113,6 +113,20 @@ JobRequests Jobs::process()
     return jobsStarted;
 }
 
+JobRequests Jobs::stop()
+{
+    // Take the queued jobs to prevent processing them.
+    const JobRequests queuedJobs = queue();
+    queue().clear();
+
+    // Wait until currently running jobs finish.
+    QFutureSynchronizer<void> waitForFinishedJobs;
+    foreach (const RunningJob &runningJob, m_running.values())
+        waitForFinishedJobs.addFuture(runningJob.future);
+
+    return queuedJobs;
+}
+
 JobRequests Jobs::runJobs(const JobRequests &jobsRequests)
 {
     JobRequests jobsStarted;
@@ -166,6 +180,11 @@ void Jobs::onJobFinished(IAsyncJob *asyncJob)
     process();
 }
 
+Jobs::JobFinishedCallback Jobs::jobFinishedCallback() const
+{
+    return m_jobFinishedCallback;
+}
+
 void Jobs::setJobFinishedCallback(const JobFinishedCallback &jobFinishedCallback)
 {
     m_jobFinishedCallback = jobFinishedCallback;
diff --git a/src/tools/clangbackend/source/clangjobs.h b/src/tools/clangbackend/source/clangjobs.h
index c2984db4b44..dd6b5d50810 100644
--- a/src/tools/clangbackend/source/clangjobs.h
+++ b/src/tools/clangbackend/source/clangjobs.h
@@ -71,6 +71,7 @@ public:
                  = PreferredTranslationUnit::RecentlyParsed);
 
     JobRequests process();
+    JobRequests stop();
 
     void setJobFinishedCallback(const JobFinishedCallback &jobFinishedCallback);
 
@@ -80,6 +81,7 @@ public /*for tests*/:
     const JobRequests &queue() const;
     bool isJobRunningForTranslationUnit(const Utf8String &translationUnitId) const;
     bool isJobRunningForJobRequest(const JobRequest &jobRequest) const;
+    JobFinishedCallback jobFinishedCallback() const;
 
 private:
     JobRequests runJobs(const JobRequests &jobRequest);
diff --git a/src/tools/clangbackend/source/clangsupportivetranslationunitinitializer.cpp b/src/tools/clangbackend/source/clangsupportivetranslationunitinitializer.cpp
index 9c162eb8cfa..b84fe431553 100644
--- a/src/tools/clangbackend/source/clangsupportivetranslationunitinitializer.cpp
+++ b/src/tools/clangbackend/source/clangsupportivetranslationunitinitializer.cpp
@@ -56,8 +56,7 @@ SupportiveTranslationUnitInitializer::State SupportiveTranslationUnitInitializer
 
 void SupportiveTranslationUnitInitializer::startInitializing()
 {
-    QTC_CHECK(m_state == State::NotInitialized);
-    if (abortIfDocumentIsClosed())
+    if (!checkStateAndDocument(State::NotInitialized))
         return;
 
     m_document.translationUnits().createAndAppend();
@@ -71,10 +70,15 @@ void SupportiveTranslationUnitInitializer::startInitializing()
     m_state = State::WaitingForParseJob;
 }
 
+void SupportiveTranslationUnitInitializer::abort()
+{
+    m_jobs.setJobFinishedCallback(Jobs::JobFinishedCallback());
+    m_state = State::Aborted;
+}
+
 void SupportiveTranslationUnitInitializer::checkIfParseJobFinished(const Jobs::RunningJob &job)
 {
-    QTC_CHECK(m_state == State::WaitingForParseJob);
-    if (abortIfDocumentIsClosed())
+    if (!checkStateAndDocument(State::WaitingForParseJob))
         return;
 
     if (job.jobRequest.type == JobRequest::Type::ParseSupportiveTranslationUnit) {
@@ -90,8 +94,7 @@ void SupportiveTranslationUnitInitializer::checkIfParseJobFinished(const Jobs::R
 
 void SupportiveTranslationUnitInitializer::checkIfReparseJobFinished(const Jobs::RunningJob &job)
 {
-    QTC_CHECK(m_state == State::WaitingForReparseJob);
-    if (abortIfDocumentIsClosed())
+    if (!checkStateAndDocument(State::WaitingForReparseJob))
         return;
 
     if (job.jobRequest.type == JobRequest::Type::ReparseSupportiveTranslationUnit) {
@@ -106,16 +109,20 @@ void SupportiveTranslationUnitInitializer::checkIfReparseJobFinished(const Jobs:
     }
 }
 
-bool SupportiveTranslationUnitInitializer::abortIfDocumentIsClosed()
+bool SupportiveTranslationUnitInitializer::checkStateAndDocument(State currentExpectedState)
 {
-    QTC_CHECK(m_isDocumentClosedChecker);
-
-    if (m_isDocumentClosedChecker(m_document.filePath(), m_document.projectPart().id())) {
+    if (m_state != currentExpectedState) {
         m_state = State::Aborted;
-        return true;
+        return false;
     }
 
-    return false;
+    QTC_CHECK(m_isDocumentClosedChecker);
+    if (m_isDocumentClosedChecker(m_document.filePath(), m_document.projectPart().id())) {
+        m_state = State::Aborted;
+        return false;
+    }
+
+    return true;
 }
 
 void SupportiveTranslationUnitInitializer::addJob(JobRequest::Type jobRequestType)
diff --git a/src/tools/clangbackend/source/clangsupportivetranslationunitinitializer.h b/src/tools/clangbackend/source/clangsupportivetranslationunitinitializer.h
index 18a01864ddc..785e145c60f 100644
--- a/src/tools/clangbackend/source/clangsupportivetranslationunitinitializer.h
+++ b/src/tools/clangbackend/source/clangsupportivetranslationunitinitializer.h
@@ -52,6 +52,7 @@ public:
 
     State state() const;
     void startInitializing();
+    void abort();
 
 public: // for tests
     void setState(const State &state);
@@ -59,7 +60,7 @@ public: // for tests
     void checkIfReparseJobFinished(const Jobs::RunningJob &job);
 
 private:
-    bool abortIfDocumentIsClosed();
+    bool checkStateAndDocument(State currentExpectedState);
     void addJob(JobRequest::Type jobRequestType);
 
 private:
diff --git a/tests/unit/unittest/clangcodemodelserver-test.cpp b/tests/unit/unittest/clangcodemodelserver-test.cpp
index 36efb1597a8..edcbcff7ade 100644
--- a/tests/unit/unittest/clangcodemodelserver-test.cpp
+++ b/tests/unit/unittest/clangcodemodelserver-test.cpp
@@ -406,6 +406,18 @@ TEST_F(ClangCodeModelServerSlowTest, TranslationUnitAfterUpdateNeedsReparse)
     ASSERT_THAT(clangServer, HasDirtyDocument(filePathA, projectPartId, 1U, true, true));
 }
 
+TEST_F(ClangCodeModelServerSlowTest, TakeOverJobsOnProjectPartChange)
+{
+    registerProjectAndFileAndWaitForFinished(filePathC, 2);
+    updateVisibilty(filePathB, filePathB); // Disable processing jobs
+    requestReferences();
+
+    expectReferences();
+
+    changeProjectPartArguments(); // Here we do not want to loose the RequestReferences job
+    updateVisibilty(filePathC, filePathC); // Enable processing jobs
+}
+
 void ClangCodeModelServer::SetUp()
 {
     clangServer.setClient(&mockClangCodeModelClient);
diff --git a/tests/unit/unittest/clangdocumentprocessors-test.cpp b/tests/unit/unittest/clangdocumentprocessors-test.cpp
index 87990bca114..0e16ab1f4e0 100644
--- a/tests/unit/unittest/clangdocumentprocessors-test.cpp
+++ b/tests/unit/unittest/clangdocumentprocessors-test.cpp
@@ -126,6 +126,19 @@ TEST_F(DocumentProcessors, Remove)
     ASSERT_TRUE(documentProcessors.processors().empty());
 }
 
+TEST_F(DocumentProcessors, ResetTakesOverJobsInQueue)
+{
+    documentProcessors.create(document);
+    documentProcessors.processor(document).addJob(JobRequest::Type::RequestReferences);
+    documents.remove({document.fileContainer()});
+    const auto newDocument = *documents.create({document.fileContainer()}).begin();
+
+    documentProcessors.reset(document, newDocument);
+
+    ASSERT_THAT(documentProcessors.processor(document).queue().first().type,
+                JobRequest::Type::RequestReferences);
+}
+
 TEST_F(DocumentProcessors, RemoveThrowsForNotExisting)
 {
     ASSERT_THROW(documentProcessors.remove(document),
diff --git a/tests/unit/unittest/clangsupportivetranslationunitinitializer-test.cpp b/tests/unit/unittest/clangsupportivetranslationunitinitializer-test.cpp
index 540fcf7fdc7..65062a9d165 100644
--- a/tests/unit/unittest/clangsupportivetranslationunitinitializer-test.cpp
+++ b/tests/unit/unittest/clangsupportivetranslationunitinitializer-test.cpp
@@ -111,6 +111,18 @@ TEST_F(SupportiveTranslationUnitInitializerSlowTest, StartInitializingStartsJob)
     ASSERT_THAT(runningJob.jobRequest.type, JobRequest::Type::ParseSupportiveTranslationUnit);
 }
 
+TEST_F(SupportiveTranslationUnitInitializerSlowTest, Abort)
+{
+    initializer.startInitializing();
+    assertSingleJobRunningAndEmptyQueue();
+
+    initializer.abort();
+
+    ASSERT_THAT(initializer.state(),
+                Eq(ClangBackEnd::SupportiveTranslationUnitInitializer::State::Aborted));
+    ASSERT_FALSE(jobs.jobFinishedCallback());
+}
+
 TEST_F(SupportiveTranslationUnitInitializer, CheckIfParseJobFinishedAbortsIfDocumentIsClosed)
 {
     documents.remove({FileContainer(filePath, projectPartId)});