diff --git a/src/plugins/clangcodemodel/clangmodelmanagersupport.cpp b/src/plugins/clangcodemodel/clangmodelmanagersupport.cpp
index 687d13c4476..afc72cee825 100644
--- a/src/plugins/clangcodemodel/clangmodelmanagersupport.cpp
+++ b/src/plugins/clangcodemodel/clangmodelmanagersupport.cpp
@@ -367,8 +367,11 @@ void ClangModelManagerSupport::updateLanguageClient(
 
             // Acquaint the client with all open C++ documents for this project.
             bool hasDocuments = false;
+            const ClangdSettings settings(ClangdProjectSettings(project).settings());
             for (TextEditor::TextDocument * const doc : allCppDocuments()) {
                 const Client * const currentClient = LanguageClientManager::clientForDocument(doc);
+                if (!settings.sizeIsOkay(doc->filePath()))
+                    continue;
                 if (!currentClient || !currentClient->project()
                         || currentClient->state() != Client::Initialized
                         || project->isKnownFile(doc->filePath())) {
@@ -466,6 +469,8 @@ void ClangModelManagerSupport::claimNonProjectSources(ClangdClient *client)
             continue;
         }
         ClangEditorDocumentProcessor::clearTextMarks(doc->filePath());
+        if (!ClangdSettings::instance().sizeIsOkay(doc->filePath()))
+            continue;
         client->openDocument(doc);
     }
 }
@@ -568,6 +573,9 @@ void ClangModelManagerSupport::onEditorOpened(Core::IEditor *editor)
 
         ProjectExplorer::Project * project
                 = ProjectExplorer::SessionManager::projectForFile(document->filePath());
+        const ClangdSettings settings(ClangdProjectSettings(project).settings());
+        if (!settings.sizeIsOkay(textDocument->filePath()))
+            return;
         if (!project)
             project = fallbackProject();
         if (ClangdClient * const client = clientForProject(project))
diff --git a/src/plugins/cppeditor/cppcodemodelsettings.cpp b/src/plugins/cppeditor/cppcodemodelsettings.cpp
index 9c7f995c064..ebad938a17e 100644
--- a/src/plugins/cppeditor/cppcodemodelsettings.cpp
+++ b/src/plugins/cppeditor/cppcodemodelsettings.cpp
@@ -78,6 +78,8 @@ static QString clangdIndexingKey() { return QLatin1String("ClangdIndexing"); }
 static QString clangdHeaderInsertionKey() { return QLatin1String("ClangdHeaderInsertion"); }
 static QString clangdThreadLimitKey() { return QLatin1String("ClangdThreadLimit"); }
 static QString clangdDocumentThresholdKey() { return QLatin1String("ClangdDocumentThreshold"); }
+static QString clangdSizeThresholdEnabledKey() { return QLatin1String("ClangdSizeThresholdEnabled"); }
+static QString clangdSizeThresholdKey() { return QLatin1String("ClangdSizeThreshold"); }
 static QString clangdUseGlobalSettingsKey() { return QLatin1String("useGlobalSettings"); }
 static QString sessionsWithOneClangdKey() { return QLatin1String("SessionsWithOneClangd"); }
 
@@ -350,6 +352,11 @@ FilePath ClangdSettings::clangdFilePath() const
     return fallbackClangdFilePath();
 }
 
+bool ClangdSettings::sizeIsOkay(const Utils::FilePath &fp) const
+{
+    return !sizeThresholdEnabled() || sizeThresholdInKb() * 1024 >= fp.fileSize();
+}
+
 ClangdSettings::Granularity ClangdSettings::granularity() const
 {
     if (m_data.sessionsWithOneClangd.contains(ProjectExplorer::SessionManager::activeSession()))
@@ -479,6 +486,8 @@ QVariantMap ClangdSettings::Data::toMap() const
     map.insert(clangdHeaderInsertionKey(), autoIncludeHeaders);
     map.insert(clangdThreadLimitKey(), workerThreadLimit);
     map.insert(clangdDocumentThresholdKey(), documentUpdateThreshold);
+    map.insert(clangdSizeThresholdEnabledKey(), sizeThresholdEnabled);
+    map.insert(clangdSizeThresholdKey(), sizeThresholdInKb);
     map.insert(sessionsWithOneClangdKey(), sessionsWithOneClangd);
     return map;
 }
@@ -491,6 +500,8 @@ void ClangdSettings::Data::fromMap(const QVariantMap &map)
     autoIncludeHeaders = map.value(clangdHeaderInsertionKey(), false).toBool();
     workerThreadLimit = map.value(clangdThreadLimitKey(), 0).toInt();
     documentUpdateThreshold = map.value(clangdDocumentThresholdKey(), 500).toInt();
+    sizeThresholdEnabled = map.value(clangdSizeThresholdEnabledKey(), false).toBool();
+    sizeThresholdInKb = map.value(clangdSizeThresholdKey(), 1024).toLongLong();
     sessionsWithOneClangd = map.value(sessionsWithOneClangdKey()).toStringList();
 }
 
diff --git a/src/plugins/cppeditor/cppcodemodelsettings.h b/src/plugins/cppeditor/cppcodemodelsettings.h
index 7550c011b2d..0d3e52247dd 100644
--- a/src/plugins/cppeditor/cppcodemodelsettings.h
+++ b/src/plugins/cppeditor/cppcodemodelsettings.h
@@ -115,17 +115,21 @@ public:
                     && s1.workerThreadLimit == s2.workerThreadLimit
                     && s1.enableIndexing == s2.enableIndexing
                     && s1.autoIncludeHeaders == s2.autoIncludeHeaders
-                    && s1.documentUpdateThreshold == s2.documentUpdateThreshold;
+                    && s1.documentUpdateThreshold == s2.documentUpdateThreshold
+                    && s1.sizeThresholdEnabled == s2.sizeThresholdEnabled
+                    && s1.sizeThresholdInKb == s2.sizeThresholdInKb;
         }
         friend bool operator!=(const Data &s1, const Data &s2) { return !(s1 == s2); }
 
         Utils::FilePath executableFilePath;
         QStringList sessionsWithOneClangd;
         int workerThreadLimit = 0;
+        int documentUpdateThreshold = 500;
+        qint64 sizeThresholdInKb = 1024;
         bool useClangd = true;
         bool enableIndexing = true;
         bool autoIncludeHeaders = false;
-        int documentUpdateThreshold = 500;
+        bool sizeThresholdEnabled = false;
     };
 
     ClangdSettings(const Data &data) : m_data(data) {}
@@ -139,6 +143,9 @@ public:
     bool autoIncludeHeaders() const { return m_data.autoIncludeHeaders; }
     int workerThreadLimit() const { return m_data.workerThreadLimit; }
     int documentUpdateThreshold() const { return m_data.documentUpdateThreshold; }
+    qint64 sizeThresholdInKb() const { return m_data.sizeThresholdInKb; }
+    bool sizeThresholdEnabled() const { return m_data.sizeThresholdEnabled; }
+    bool sizeIsOkay(const Utils::FilePath &fp) const;
 
     enum class Granularity { Project, Session };
     Granularity granularity() const;
diff --git a/src/plugins/cppeditor/cppcodemodelsettingspage.cpp b/src/plugins/cppeditor/cppcodemodelsettingspage.cpp
index 780ae671ccd..7b1af0fe72a 100644
--- a/src/plugins/cppeditor/cppcodemodelsettingspage.cpp
+++ b/src/plugins/cppeditor/cppcodemodelsettingspage.cpp
@@ -50,6 +50,8 @@
 #include <QVBoxLayout>
 #include <QVersionNumber>
 
+#include <limits>
+
 namespace CppEditor::Internal {
 
 class CppCodeModelSettingsWidget final : public Core::IOptionsPageWidget
@@ -206,8 +208,10 @@ public:
     QCheckBox useClangdCheckBox;
     QCheckBox indexingCheckBox;
     QCheckBox autoIncludeHeadersCheckBox;
+    QCheckBox sizeThresholdCheckBox;
     QSpinBox threadLimitSpinBox;
     QSpinBox documentUpdateThreshold;
+    QSpinBox sizeThresholdSpinBox;
     Utils::PathChooser clangdChooser;
     Utils::InfoLabel versionWarningLabel;
     QGroupBox *sessionsGroupBox = nullptr;
@@ -243,6 +247,15 @@ ClangdSettingsWidget::ClangdSettingsWidget(const ClangdSettings::Data &settingsD
         tr("Defines the amount of time Qt Creator waits before sending document changes to the "
            "server.\n"
            "If the document changes again while waiting, this timeout resets.\n"));
+    d->sizeThresholdCheckBox.setText(tr("Ignore files greater than"));
+    d->sizeThresholdCheckBox.setChecked(settings.sizeThresholdEnabled());
+    d->sizeThresholdSpinBox.setMinimum(1);
+    d->sizeThresholdSpinBox.setMaximum(std::numeric_limits<int>::max());
+    d->sizeThresholdSpinBox.setSuffix(" KB");
+    d->sizeThresholdSpinBox.setValue(settings.sizeThresholdInKb());
+    d->sizeThresholdSpinBox.setToolTip(tr(
+            "Files greater than this will not be opened as documents in clangd.\n"
+            "The built-in code model will handle highlighting, completion and so on."));
 
     const auto layout = new QVBoxLayout(this);
     layout->setContentsMargins(0, 0, 0, 0);
@@ -265,6 +278,10 @@ ClangdSettingsWidget::ClangdSettingsWidget(const ClangdSettings::Data &settingsD
     documentUpdateThresholdLayout->addStretch(1);
     const auto documentUpdateThresholdLabel = new QLabel(tr("Document update threshold:"));
     formLayout->addRow(documentUpdateThresholdLabel, documentUpdateThresholdLayout);
+    const auto sizeThresholdLayout = new QHBoxLayout;
+    sizeThresholdLayout->addWidget(&d->sizeThresholdSpinBox);
+    sizeThresholdLayout->addStretch(1);
+    formLayout->addRow(&d->sizeThresholdCheckBox, sizeThresholdLayout);
     layout->addLayout(formLayout);
 
     if (!isForProject) {
@@ -381,6 +398,10 @@ ClangdSettingsWidget::ClangdSettingsWidget(const ClangdSettings::Data &settingsD
             this, &ClangdSettingsWidget::settingsDataChanged);
     connect(&d->threadLimitSpinBox, qOverload<int>(&QSpinBox::valueChanged),
             this, &ClangdSettingsWidget::settingsDataChanged);
+    connect(&d->sizeThresholdCheckBox, &QCheckBox::toggled,
+            this, &ClangdSettingsWidget::settingsDataChanged);
+    connect(&d->sizeThresholdSpinBox, qOverload<int>(&QSpinBox::valueChanged),
+            this, &ClangdSettingsWidget::settingsDataChanged);
     connect(&d->clangdChooser, &Utils::PathChooser::pathChanged,
             this, &ClangdSettingsWidget::settingsDataChanged);
 }
@@ -399,6 +420,8 @@ ClangdSettings::Data ClangdSettingsWidget::settingsData() const
     data.autoIncludeHeaders = d->autoIncludeHeadersCheckBox.isChecked();
     data.workerThreadLimit = d->threadLimitSpinBox.value();
     data.documentUpdateThreshold = d->documentUpdateThreshold.value();
+    data.sizeThresholdEnabled = d->sizeThresholdCheckBox.isChecked();
+    data.sizeThresholdInKb = d->sizeThresholdSpinBox.value();
     data.sessionsWithOneClangd = d->sessionsModel.stringList();
     return data;
 }