diff --git a/src/plugins/clangcodemodel/clangdclient.cpp b/src/plugins/clangcodemodel/clangdclient.cpp
index 7c307de4ac2..7dd6ee92cd1 100644
--- a/src/plugins/clangcodemodel/clangdclient.cpp
+++ b/src/plugins/clangcodemodel/clangdclient.cpp
@@ -383,7 +383,7 @@ static void addToCompilationDb(QJsonObject &cdb,
     const QString fileString = sourceFile.path.toUserOutput();
     args.append(fileString);
     QJsonObject value;
-    value.insert("workingDirectory", workingDir.toString());
+    value.insert("workingDirectory", workingDir.path());
     value.insert("compilationCommand", args);
     cdb.insert(fileString, value);
 }
@@ -520,13 +520,20 @@ void ClangdClient::openExtraFile(const Utils::FilePath &filePath, const QString
         return;
     }
 
-    QFile cxxFile(filePath.toString());
-    if (content.isEmpty() && !cxxFile.open(QIODevice::ReadOnly))
-        return;
+    QString text;
+    if (!content.isEmpty()) {
+        text = content;
+    } else {
+        expected_str<QByteArray> fileContent = filePath.fileContents();
+        if (!fileContent)
+            return;
+        text = QString::fromUtf8(*std::move(fileContent));
+    }
+
     TextDocumentItem item;
     item.setLanguageId("cpp");
     item.setUri(hostPathToServerUri(filePath));
-    item.setText(!content.isEmpty() ? content : QString::fromUtf8(cxxFile.readAll()));
+    item.setText(std::move(text));
     item.setVersion(0);
     sendMessage(DidOpenTextDocumentNotification(DidOpenTextDocumentParams(item)),
                 SendDocUpdates::Ignore);
@@ -918,8 +925,7 @@ void ClangdClient::updateParserConfig(const Utils::FilePath &filePath,
     CppEditor::CompilerOptionsBuilder optionsBuilder = clangOptionsBuilder(
                 *projectPart, warningsConfigForProject(project()), includeDir,
                 ProjectExplorer::Macro::toMacros(config.editorDefines));
-    const CppEditor::ProjectFile file(filePath,
-                                      CppEditor::ProjectFile::classify(filePath.toString()));
+    const CppEditor::ProjectFile file(filePath, CppEditor::ProjectFile::classify(filePath));
     const QJsonArray projectPartOptions = fullProjectPartOptions(
                 optionsBuilder, globalClangOptions());
     const auto cppSettings = CppEditor::CppCodeModelSettings::settingsForProject(
diff --git a/src/plugins/clangcodemodel/clangdcompletion.cpp b/src/plugins/clangcodemodel/clangdcompletion.cpp
index 4ff9c748f4f..c485cef860e 100644
--- a/src/plugins/clangcodemodel/clangdcompletion.cpp
+++ b/src/plugins/clangcodemodel/clangdcompletion.cpp
@@ -321,7 +321,7 @@ bool ClangdCompletionAssistProvider::isContinuationChar(const QChar &c) const
 bool ClangdCompletionAssistProvider::isInCommentOrString(const AssistInterface *interface) const
 {
     LanguageFeatures features = LanguageFeatures::defaultFeatures();
-    features.objCEnabled = ProjectFile::isObjC(interface->filePath().toString());
+    features.objCEnabled = ProjectFile::isObjC(interface->filePath());
     return CppEditor::isInCommentOrString(interface, features);
 }
 
@@ -543,7 +543,7 @@ IAssistProposal *CustomAssistProcessor::perform()
              : CppCompletionAssistProcessor::preprocessorCompletions()) {
             completions << createItem(completion, macroIcon);
         }
-        if (ProjectFile::isObjC(interface()->filePath().toString()))
+        if (ProjectFile::isObjC(interface()->filePath()))
             completions << createItem("import", macroIcon);
         break;
     }
diff --git a/src/plugins/clangcodemodel/clangdfindreferences.cpp b/src/plugins/clangcodemodel/clangdfindreferences.cpp
index 13968801e7b..4d6e7da9238 100644
--- a/src/plugins/clangcodemodel/clangdfindreferences.cpp
+++ b/src/plugins/clangcodemodel/clangdfindreferences.cpp
@@ -191,22 +191,23 @@ ClangdFindReferences::ClangdFindReferences(ClangdClient *client, const Link &lin
     d->categorize = true;
     d->search = search;
 
-    if (!client->documentForFilePath(link.targetFilePath)) {
-        QFile f(link.targetFilePath.toString());
-        if (!f.open(QIODevice::ReadOnly)) {
+    const FilePath &targetFilePath = link.targetFilePath;
+    if (!client->documentForFilePath(targetFilePath)) {
+        expected_str<QByteArray> fileContents = targetFilePath.fileContents();
+        if (!fileContents) {
             d->finishSearch();
             return;
         }
-        const QString contents = QString::fromUtf8(f.readAll());
+        const QString contents = QString::fromUtf8(*std::move(fileContents));
         QTextDocument doc(contents);
         QTextCursor cursor(&doc);
         cursor.setPosition(Text::positionInText(&doc, link.targetLine, link.targetColumn + 1));
         cursor.select(QTextCursor::WordUnderCursor);
         d->searchTerm = cursor.selectedText();
-        client->openExtraFile(link.targetFilePath, contents);
+        client->openExtraFile(targetFilePath, contents);
         d->checkUnusedData->openedExtraFileForLink = true;
     }
-    const TextDocumentIdentifier documentId(client->hostPathToServerUri(link.targetFilePath));
+    const TextDocumentIdentifier documentId(client->hostPathToServerUri(targetFilePath));
     const Position pos(link.targetLine - 1, link.targetColumn);
     ReferenceParams params(TextDocumentPositionParams(documentId, pos));
     params.setContext(ReferenceParams::ReferenceContext(true));
diff --git a/src/plugins/clangcodemodel/clangdiagnostictooltipwidget.cpp b/src/plugins/clangcodemodel/clangdiagnostictooltipwidget.cpp
index b415eb23ef6..681294e06e7 100644
--- a/src/plugins/clangcodemodel/clangdiagnostictooltipwidget.cpp
+++ b/src/plugins/clangcodemodel/clangdiagnostictooltipwidget.cpp
@@ -31,11 +31,11 @@ namespace {
 const char LINK_ACTION_GOTO_LOCATION[] = "#gotoLocation";
 const char LINK_ACTION_APPLY_FIX[] = "#applyFix";
 
-QString fileNamePrefix(const QString &mainFilePath, const Utils::Link &location)
+QString fileNamePrefix(const Utils::FilePath &mainFilePath, const Utils::Link &location)
 {
-    const QString filePath = location.targetFilePath.toString();
+    const Utils::FilePath &filePath = location.targetFilePath;
     if (!filePath.isEmpty() && filePath != mainFilePath)
-        return QFileInfo(filePath).fileName() + QLatin1Char(':');
+        return filePath.fileName() + QLatin1Char(':');
 
     return QString();
 }
@@ -175,8 +175,8 @@ private:
     QString tableRows(const ClangDiagnostic &diagnostic)
     {
         m_mainFilePath = m_displayHints.showFileNameInMainDiagnostic
-                ? QString()
-                : diagnostic.location.targetFilePath.toString();
+                             ? Utils::FilePath{}
+                             : diagnostic.location.targetFilePath;
 
         const ClangDiagnostic diag = supplementedDiagnostic(diagnostic);
 
@@ -253,8 +253,8 @@ private:
         return text;
     }
 
-    QString clickableLocation(const ClangDiagnostic &diagnostic, const QString &mainFilePath,
-                              bool &hasContent)
+    QString clickableLocation(
+        const ClangDiagnostic &diagnostic, const Utils::FilePath &mainFilePath, bool &hasContent)
     {
         const Utils::Link &location = diagnostic.location;
 
@@ -331,7 +331,7 @@ private:
     TargetIdToDiagnosticTable m_targetIdsToDiagnostics;
     unsigned m_targetIdCounter = 0;
 
-    QString m_mainFilePath;
+    Utils::FilePath m_mainFilePath;
 };
 
 WidgetFromDiagnostics::DisplayHints toHints(const ClangDiagnosticWidget::Destination &destination,
diff --git a/src/plugins/clangcodemodel/clangfixitoperation.cpp b/src/plugins/clangcodemodel/clangfixitoperation.cpp
index 802bdd17bbb..9e989781351 100644
--- a/src/plugins/clangcodemodel/clangfixitoperation.cpp
+++ b/src/plugins/clangcodemodel/clangfixitoperation.cpp
@@ -13,7 +13,7 @@
 namespace ClangCodeModel {
 namespace Internal {
 
-using FileToFixits = QMap<QString, QList<ClangFixIt>>;
+using FileToFixits = QMap<Utils::FilePath, QList<ClangFixIt>>;
 using RefactoringFilePtr = QSharedPointer<TextEditor::RefactoringFile>;
 
 ClangFixItOperation::ClangFixItOperation(const QString &fixItText, const QList<ClangFixIt> &fixIts)
@@ -36,8 +36,8 @@ static FileToFixits fixitsPerFile(const QList<ClangFixIt> &fixIts)
     FileToFixits mapping;
 
     for (const auto &fixItContainer : fixIts) {
-        const QString rangeStartFilePath = fixItContainer.range.start.targetFilePath.toString();
-        const QString rangeEndFilePath = fixItContainer.range.end.targetFilePath.toString();
+        const Utils::FilePath &rangeStartFilePath = fixItContainer.range.start.targetFilePath;
+        const Utils::FilePath &rangeEndFilePath = fixItContainer.range.end.targetFilePath;
         QTC_CHECK(rangeStartFilePath == rangeEndFilePath);
         mapping[rangeStartFilePath].append(fixItContainer);
     }
@@ -52,11 +52,10 @@ void ClangFixItOperation::perform()
     const FileToFixits fileToFixIts = fixitsPerFile(fixIts);
 
     for (auto i = fileToFixIts.cbegin(), end = fileToFixIts.cend(); i != end; ++i) {
-        const QString filePath = i.key();
-        const QList<ClangFixIt> fixits = i.value();
+        const Utils::FilePath &filePath = i.key();
+        const QList<ClangFixIt> &fixits = i.value();
 
-        RefactoringFilePtr refactoringFile = refactoringChanges.file(
-            Utils::FilePath::fromString(filePath));
+        RefactoringFilePtr refactoringFile = refactoringChanges.file(filePath);
         refactoringFiles.append(refactoringFile);
 
         applyFixitsToFile(*refactoringFile, fixits);
diff --git a/src/plugins/clangcodemodel/clangmodelmanagersupport.cpp b/src/plugins/clangcodemodel/clangmodelmanagersupport.cpp
index f974a52af8a..ace76461d85 100644
--- a/src/plugins/clangcodemodel/clangmodelmanagersupport.cpp
+++ b/src/plugins/clangcodemodel/clangmodelmanagersupport.cpp
@@ -800,7 +800,7 @@ void ClangModelManagerSupport::watchForExternalChanges()
         if (!LanguageClientManager::hasClients<ClangdClient>())
             return;
         for (const FilePath &file : files) {
-            const ProjectFile::Kind kind = ProjectFile::classify(file.toString());
+            const ProjectFile::Kind kind = ProjectFile::classify(file);
             if (!ProjectFile::isSource(kind) && !ProjectFile::isHeader(kind))
                 continue;
             Project * const project = ProjectManager::projectForFile(file);
@@ -842,7 +842,7 @@ void ClangModelManagerSupport::watchForInternalChanges()
     connect(DocumentManager::instance(), &DocumentManager::filesChangedInternally,
             this, [this](const FilePaths &filePaths) {
         for (const FilePath &fp : filePaths) {
-            const ProjectFile::Kind kind = ProjectFile::classify(fp.toString());
+            const ProjectFile::Kind kind = ProjectFile::classify(fp);
             if (!ProjectFile::isSource(kind) && !ProjectFile::isHeader(kind))
                 continue;
             Project * const project = ProjectManager::projectForFile(fp);
diff --git a/src/plugins/cppeditor/cppprojectfile.cpp b/src/plugins/cppeditor/cppprojectfile.cpp
index 580ad1762da..cf3429d0ec5 100644
--- a/src/plugins/cppeditor/cppprojectfile.cpp
+++ b/src/plugins/cppeditor/cppprojectfile.cpp
@@ -11,6 +11,16 @@
 
 namespace CppEditor {
 
+template<typename T>
+static ProjectFile::Kind classifyImpl(T &&file)
+{
+    if (ProjectFile::isAmbiguousHeader(file))
+        return ProjectFile::Kind::AmbiguousHeader;
+
+    const Utils::MimeType mimeType = Utils::mimeTypeForFile(file);
+    return ProjectFile::classifyByMimeType(mimeType.name());
+}
+
 ProjectFile::ProjectFile(const Utils::FilePath &filePath, Kind kind, bool active)
     : path(filePath)
     , kind(kind)
@@ -53,16 +63,22 @@ ProjectFile::Kind ProjectFile::classifyByMimeType(const QString &mt)
 
 ProjectFile::Kind ProjectFile::classify(const QString &filePath)
 {
-    if (isAmbiguousHeader(filePath))
-        return AmbiguousHeader;
-
-    const Utils::MimeType mimeType = Utils::mimeTypeForFile(filePath);
-    return classifyByMimeType(mimeType.name());
+    return classifyImpl(filePath);
 }
 
-bool ProjectFile::isAmbiguousHeader(const QString &filePath)
+ProjectFile::Kind ProjectFile::classify(const Utils::FilePath &filePath)
 {
-    return filePath.endsWith(".h");
+    return classifyImpl(filePath);
+}
+
+bool ProjectFile::isAmbiguousHeader(QStringView filePath)
+{
+    return filePath.endsWith(u".h");
+}
+
+bool ProjectFile::isAmbiguousHeader(const Utils::FilePath &filePath)
+{
+    return isAmbiguousHeader(filePath.fileNameView());
 }
 
 bool ProjectFile::isObjC(const QString &filePath)
@@ -70,6 +86,11 @@ bool ProjectFile::isObjC(const QString &filePath)
     return isObjC(classify(filePath));
 }
 
+bool ProjectFile::isObjC(const Utils::FilePath &filePath)
+{
+    return isObjC(classify(filePath));
+}
+
 bool ProjectFile::isObjC(Kind kind)
 {
     switch (kind) {
@@ -131,7 +152,7 @@ bool ProjectFile::isHeader(ProjectFile::Kind kind)
 
 bool ProjectFile::isHeader(const Utils::FilePath &fp)
 {
-    return isHeader(classify(fp.toString()));
+    return isHeader(classify(fp));
 }
 
 bool ProjectFile::isSource(ProjectFile::Kind kind)
diff --git a/src/plugins/cppeditor/cppprojectfile.h b/src/plugins/cppeditor/cppprojectfile.h
index 529d0bb6558..3451603d18e 100644
--- a/src/plugins/cppeditor/cppprojectfile.h
+++ b/src/plugins/cppeditor/cppprojectfile.h
@@ -35,6 +35,7 @@ public:
 
     static Kind classifyByMimeType(const QString &mt);
     static Kind classify(const QString &filePath);
+    static Kind classify(const Utils::FilePath &filePath);
 
     static Kind sourceForHeaderKind(Kind kind);
     static Kind sourceKind(Kind kind);
@@ -44,8 +45,10 @@ public:
     static bool isHeader(const Utils::FilePath &fp);
     static bool isC(Kind kind);
     static bool isCxx(Kind kind);
-    static bool isAmbiguousHeader(const QString &filePath);
+    static bool isAmbiguousHeader(QStringView filePath);
+    static bool isAmbiguousHeader(const Utils::FilePath &filePath);
     static bool isObjC(const QString &filePath);
+    static bool isObjC(const Utils::FilePath &filePath);
     static bool isObjC(Kind kind);
 
     bool isHeader() const;