diff --git a/src/tools/clangbackend/ipcsource/translationunit.cpp b/src/tools/clangbackend/ipcsource/translationunit.cpp
index f74b555f383..17871176fae 100644
--- a/src/tools/clangbackend/ipcsource/translationunit.cpp
+++ b/src/tools/clangbackend/ipcsource/translationunit.cpp
@@ -52,7 +52,8 @@ public:
     ~TranslationUnitData();
 
 public:
-    time_point lastChangeTimePoint;
+    time_point lastProjectPartChangeTimePoint;
+    time_point lastUnsavedFilesChangeTimePoint;
     ProjectPart projectPart;
     Utf8String filePath;
     CXTranslationUnit translationUnit = nullptr;
@@ -63,7 +64,8 @@ public:
 TranslationUnitData::TranslationUnitData(const Utf8String &filePath,
                                          const UnsavedFiles &unsavedFiles,
                                          const ProjectPart &projectPart)
-    : lastChangeTimePoint(std::chrono::steady_clock::now()),
+    : lastProjectPartChangeTimePoint(std::chrono::steady_clock::now()),
+      lastUnsavedFilesChangeTimePoint(lastProjectPartChangeTimePoint),
       projectPart(projectPart),
       filePath(filePath),
       unsavedFiles(unsavedFiles)
@@ -109,10 +111,9 @@ CXIndex TranslationUnit::index() const
 CXTranslationUnit TranslationUnit::cxTranslationUnit() const
 {
     checkIfNull();
-
-    removeOutdatedTranslationUnit();
-
+    removeTranslationUnitIfProjectPartWasChanged();
     createTranslationUnitIfNeeded();
+    reparseTranslationUnitIfUnsavedFilesAreChanged();
 
     return d->translationUnit;
 }
@@ -131,9 +132,19 @@ const Utf8String &TranslationUnit::projectPartId() const
     return d->projectPart.projectPartId();
 }
 
-const time_point &TranslationUnit::lastChangeTimePoint() const
+const time_point &TranslationUnit::lastProjectPartChangeTimePoint() const
 {
-    return d->lastChangeTimePoint;
+    return d->lastProjectPartChangeTimePoint;
+}
+
+const time_point &TranslationUnit::lastUnsavedFilesChangeTimePoint() const
+{
+    return d->lastUnsavedFilesChangeTimePoint;
+}
+
+bool TranslationUnit::isNeedingReparse() const
+{
+    return d->lastUnsavedFilesChangeTimePoint < d->unsavedFiles.lastChangeTimePoint();
 }
 
 void TranslationUnit::checkIfNull() const
@@ -148,19 +159,29 @@ void TranslationUnit::checkIfFileExists() const
         throw TranslationUnitFileNotExitsException(d->filePath);
 }
 
-void TranslationUnit::updateLastChangeTimePoint() const
+void TranslationUnit::updateLastProjectPartChangeTimePoint() const
 {
-    d->lastChangeTimePoint = std::chrono::steady_clock::now();
+    d->lastProjectPartChangeTimePoint = std::chrono::steady_clock::now();
 }
 
-void TranslationUnit::removeOutdatedTranslationUnit() const
+void TranslationUnit::updateLastUnsavedFilesChangeTimePoint() const
 {
-    if (d->projectPart.lastChangeTimePoint() >= d->lastChangeTimePoint) {
+    d->lastUnsavedFilesChangeTimePoint = std::chrono::steady_clock::now();
+}
+
+void TranslationUnit::removeTranslationUnitIfProjectPartWasChanged() const
+{
+    if (projectPartIsOutdated()) {
         clang_disposeTranslationUnit(d->translationUnit);
         d->translationUnit = nullptr;
     }
 }
 
+bool TranslationUnit::projectPartIsOutdated() const
+{
+    return d->projectPart.lastChangeTimePoint() >= d->lastProjectPartChangeTimePoint;
+}
+
 void TranslationUnit::createTranslationUnitIfNeeded() const
 {
     if (!d->translationUnit) {
@@ -180,7 +201,7 @@ void TranslationUnit::createTranslationUnitIfNeeded() const
         // e.g. clang_codeCompleteAt() dramatically.
         reparseTranslationUnit();
 
-        updateLastChangeTimePoint();
+        updateLastProjectPartChangeTimePoint();
     }
 }
 
@@ -198,6 +219,14 @@ void TranslationUnit::reparseTranslationUnit() const
                                  d->unsavedFiles.count(),
                                  d->unsavedFiles.cxUnsavedFiles(),
                                  clang_defaultReparseOptions(d->translationUnit));
+
+    updateLastUnsavedFilesChangeTimePoint();
+}
+
+void TranslationUnit::reparseTranslationUnitIfUnsavedFilesAreChanged() const
+{
+    if (isNeedingReparse())
+        reparseTranslationUnit();
 }
 
 int TranslationUnit::defaultOptions()
diff --git a/src/tools/clangbackend/ipcsource/translationunit.h b/src/tools/clangbackend/ipcsource/translationunit.h
index 75dd39e8614..5491f0acec8 100644
--- a/src/tools/clangbackend/ipcsource/translationunit.h
+++ b/src/tools/clangbackend/ipcsource/translationunit.h
@@ -82,16 +82,23 @@ public:
     const Utf8String &filePath() const;
     const Utf8String &projectPartId() const;
 
-    const time_point &lastChangeTimePoint() const;
+    const time_point &lastProjectPartChangeTimePoint() const;
+    const time_point &lastUnsavedFilesChangeTimePoint() const;
+
+    bool isNeedingReparse() const;
 
 private:
     void checkIfNull() const;
     void checkIfFileExists() const;
-    void updateLastChangeTimePoint() const;
-    void removeOutdatedTranslationUnit() const;
+    void updateLastProjectPartChangeTimePoint() const;
+    void updateLastUnsavedFilesChangeTimePoint() const;
+    void removeTranslationUnitIfProjectPartWasChanged() const;
+    bool projectPartIsOutdated() const;
     void createTranslationUnitIfNeeded() const;
     void checkTranslationUnitErrorCode(CXErrorCode errorCode) const;
     void reparseTranslationUnit() const;
+    void reparseTranslationUnitIfUnsavedFilesAreChanged() const;
+    void printIncludes() const;
     static int defaultOptions();
 
 private:
diff --git a/tests/unit/unittest/translationunittest.cpp b/tests/unit/unittest/translationunittest.cpp
index 25235940bf0..29ae9cd4686 100644
--- a/tests/unit/unittest/translationunittest.cpp
+++ b/tests/unit/unittest/translationunittest.cpp
@@ -132,15 +132,75 @@ TEST(TranslationUnit, ResetedTranslationUnitIsNull)
     ASSERT_TRUE(translationUnit.isNull());
 }
 
-TEST(TranslationUnit, TimeStampIsUpdatedAsNewCxTranslationUnitIsGenerated)
+TEST(TranslationUnit, TimeStampForProjectPartChangeIsUpdatedAsNewCxTranslationUnitIsGenerated)
 {
     TranslationUnit translationUnit(Utf8StringLiteral(TESTDATA_DIR"/complete_testfile_1.cpp"), UnsavedFiles(), ProjectPart(Utf8StringLiteral("/path/to/projectfile")));
-    auto lastChangeTimePoint = translationUnit.lastChangeTimePoint();
+    auto lastChangeTimePoint = translationUnit.lastProjectPartChangeTimePoint();
     std::this_thread::sleep_for(std::chrono::steady_clock::duration(1));
 
     translationUnit.cxTranslationUnit();
 
-    ASSERT_THAT(translationUnit.lastChangeTimePoint(), Gt(lastChangeTimePoint));
+    ASSERT_THAT(translationUnit.lastProjectPartChangeTimePoint(), Gt(lastChangeTimePoint));
+}
+
+TEST(TranslationUnit, TimeStampForProjectPartChangeIsUpdatedAsProjectPartIsCleared)
+{
+    ProjectPart projectPart(Utf8StringLiteral("/path/to/projectfile"));
+    TranslationUnit translationUnit(Utf8StringLiteral(TESTDATA_DIR"/complete_testfile_1.cpp"), UnsavedFiles(), projectPart);
+    translationUnit.cxTranslationUnit();
+    auto lastChangeTimePoint = translationUnit.lastProjectPartChangeTimePoint();
+    std::this_thread::sleep_for(std::chrono::steady_clock::duration(1));
+
+    projectPart.clear();
+    translationUnit.cxTranslationUnit();
+
+    ASSERT_THAT(translationUnit.lastProjectPartChangeTimePoint(), Gt(lastChangeTimePoint));
+}
+
+TEST(TranslationUnit, ReparseIsNeededAfterUnsavedFilesAreChanged)
+{
+    UnsavedFiles unsavedFiles;
+    TranslationUnit translationUnit(Utf8StringLiteral(TESTDATA_DIR"/complete_testfile_1.cpp"),
+                                    unsavedFiles,
+                                    ProjectPart(Utf8StringLiteral("/path/to/projectfile")));
+    translationUnit.cxTranslationUnit();
+    unsavedFiles.clear();
+    translationUnit.cxTranslationUnit();
+
+    unsavedFiles.clear();
+
+    ASSERT_TRUE(translationUnit.isNeedingReparse());
+}
+
+TEST(TranslationUnit, NeedsNoReparseAfterUnsavedFilesAreNotChanged)
+{
+    UnsavedFiles unsavedFiles;
+    TranslationUnit translationUnit(Utf8StringLiteral(TESTDATA_DIR"/complete_testfile_1.cpp"),
+                                    unsavedFiles,
+                                    ProjectPart(Utf8StringLiteral("/path/to/projectfile")));
+    translationUnit.cxTranslationUnit();
+    unsavedFiles.clear();
+    translationUnit.cxTranslationUnit();
+
+    ASSERT_FALSE(translationUnit.isNeedingReparse());
+}
+
+TEST(TranslationUnit, TimeStampForUnsavedFilesChange)
+{
+    UnsavedFiles unsavedFiles;
+    TranslationUnit translationUnit(Utf8StringLiteral(TESTDATA_DIR"/complete_testfile_1.cpp"),
+                                    unsavedFiles,
+                                    ProjectPart(Utf8StringLiteral("/path/to/projectfile")));
+    translationUnit.cxTranslationUnit();
+    unsavedFiles.clear();
+    translationUnit.cxTranslationUnit();
+    auto lastChangeTimePoint = translationUnit.lastUnsavedFilesChangeTimePoint();
+    std::this_thread::sleep_for(std::chrono::steady_clock::duration(1));
+
+    unsavedFiles.clear();
+    translationUnit.cxTranslationUnit();
+
+    ASSERT_THAT(translationUnit.lastUnsavedFilesChangeTimePoint(), Gt(lastChangeTimePoint));
 }