diff --git a/Extension/package.json b/Extension/package.json
index 5c42a5ecd..45d666a38 100644
--- a/Extension/package.json
+++ b/Extension/package.json
@@ -3990,6 +3990,11 @@
                 "title": "%c_cpp.command.switchHeaderSource.title%",
                 "category": "C/C++"
             },
+            {
+                "command": "C_Cpp.SelectTranslationUnit",
+                "title": "%c_cpp.command.selectTranslationUnit.title%",
+                "category": "C/C++"
+            },
             {
                 "command": "C_Cpp.EnableErrorSquiggles",
                 "title": "%c_cpp.command.enableErrorSquiggles.title%",
@@ -6537,6 +6542,10 @@
                     "command": "C_Cpp.SwitchHeaderSource",
                     "when": "editorLangId =~ /^(c|(cuda-)?cpp)$/ && !(config.C_Cpp.intelliSenseEngine =~ /^[dD]isabled$/)"
                 },
+                {
+                    "command": "C_Cpp.SelectTranslationUnit",
+                    "when": "editorLangId =~ /^(c|(cuda-)?cpp)$/ && config.C_Cpp.intelliSenseEngine =~ /^[dD]efault$/"
+                },
                 {
                     "command": "C_Cpp.EnableErrorSquiggles",
                     "when": "config.C_Cpp.intelliSenseEngine =~ /^[dD]efault$/"
diff --git a/Extension/package.nls.json b/Extension/package.nls.json
index 686234a1f..ea6352bef 100644
--- a/Extension/package.nls.json
+++ b/Extension/package.nls.json
@@ -15,6 +15,7 @@
     "c_cpp.command.installCompiler.title": "Install a C++ Compiler",
     "c_cpp.command.rescanCompilers.title": "Rescan for Compilers",
     "c_cpp.command.switchHeaderSource.title": "Switch Header/Source",
+    "c_cpp.command.selectTranslationUnit.title": "Select a Translation Unit...",
     "c_cpp.command.enableErrorSquiggles.title": "Enable Error Squiggles",
     "c_cpp.command.disableErrorSquiggles.title": "Disable Error Squiggles",
     "c_cpp.command.toggleDimInactiveRegions.title": "Toggle Inactive Region Colorization",
diff --git a/Extension/src/LanguageServer/client.ts b/Extension/src/LanguageServer/client.ts
index 67836f6f3..573ae1d36 100644
--- a/Extension/src/LanguageServer/client.ts
+++ b/Extension/src/LanguageServer/client.ts
@@ -216,6 +216,16 @@ interface SwitchHeaderSourceParams extends WorkspaceFolderParams {
     switchHeaderSourceFileName: string;
 }
 
+interface GetTranslationUnitSourceCandidatesResult {
+    candidates: string[];
+    currentTranslationUnit: string;
+}
+
+interface SelectTranslationUnitParams {
+    uri: string;
+    translationUnit: string;
+}
+
 interface FileChangedParams extends WorkspaceFolderParams {
     uri: string;
 }
@@ -625,6 +635,7 @@ const PreInitializationRequest: RequestType<void, string, void> = new RequestTyp
 const InitializationRequest: RequestType<CppInitializationParams, CppInitializationResult, void> = new RequestType<CppInitializationParams, CppInitializationResult, void>('cpptools/initialize');
 const QueryCompilerDefaultsRequest: RequestType<QueryDefaultCompilerParams, configs.CompilerDefaults, void> = new RequestType<QueryDefaultCompilerParams, configs.CompilerDefaults, void>('cpptools/queryCompilerDefaults');
 const SwitchHeaderSourceRequest: RequestType<SwitchHeaderSourceParams, string, void> = new RequestType<SwitchHeaderSourceParams, string, void>('cpptools/didSwitchHeaderSource');
+const GetTranslationUnitSourceCandidatesRequest: RequestType<TextDocumentIdentifier, GetTranslationUnitSourceCandidatesResult, void> = new RequestType<TextDocumentIdentifier, GetTranslationUnitSourceCandidatesResult, void>('cpptools/getTranslationUnitSourceCandidates');
 const GetDiagnosticsRequest: RequestType<void, GetDiagnosticsResult, void> = new RequestType<void, GetDiagnosticsResult, void>('cpptools/getDiagnostics');
 export const GetDocumentSymbolRequest: RequestType<GetDocumentSymbolRequestParams, GetDocumentSymbolResult, void> = new RequestType<GetDocumentSymbolRequestParams, GetDocumentSymbolResult, void>('cpptools/getDocumentSymbols');
 export const GetSymbolInfoRequest: RequestType<WorkspaceSymbolParams, LocalizeSymbolInformation[], void> = new RequestType<WorkspaceSymbolParams, LocalizeSymbolInformation[], void>('cpptools/getWorkspaceSymbols');
@@ -653,6 +664,7 @@ const PauseParsingNotification: NotificationType<void> = new NotificationType<vo
 const ResumeParsingNotification: NotificationType<void> = new NotificationType<void>('cpptools/resumeParsing');
 const DidChangeActiveEditorNotification: NotificationType<DidChangeActiveEditorParams> = new NotificationType<DidChangeActiveEditorParams>('cpptools/didChangeActiveEditor');
 const RestartIntelliSenseForFileNotification: NotificationType<TextDocumentIdentifier> = new NotificationType<TextDocumentIdentifier>('cpptools/restartIntelliSenseForFile');
+const SelectTranslationUnitNotification: NotificationType<SelectTranslationUnitParams> = new NotificationType<SelectTranslationUnitParams>('cpptools/selectTranslationUnit');
 const DidChangeTextEditorSelectionNotification: NotificationType<Range> = new NotificationType<Range>('cpptools/didChangeTextEditorSelection');
 const ChangeCompileCommandsNotification: NotificationType<FileChangedParams> = new NotificationType<FileChangedParams>('cpptools/didChangeCompileCommands');
 const ChangeSelectedSettingNotification: NotificationType<FolderSelectedSettingParams> = new NotificationType<FolderSelectedSettingParams>('cpptools/didChangeSelectedSetting');
@@ -832,6 +844,8 @@ export interface Client {
     takeOwnership(document: vscode.TextDocument): void;
     sendDidOpen(document: vscode.TextDocument): Promise<void>;
     requestSwitchHeaderSource(rootUri: vscode.Uri, fileName: string, token: vscode.CancellationToken): Thenable<string>;
+    getTranslationUnitSourceCandidates(uri: vscode.Uri, token: vscode.CancellationToken): Promise<GetTranslationUnitSourceCandidatesResult>;
+    selectTranslationUnit(uri: vscode.Uri, translationUnit: string): Promise<void>;
     updateActiveDocumentTextOptions(): void;
     didChangeActiveEditor(editor?: vscode.TextEditor, selection?: Range): Promise<void>;
     restartIntelliSenseForFile(document: vscode.TextDocument): Promise<void>;
@@ -2759,7 +2773,7 @@ export class DefaultClient implements Client {
                 const isTrackedFile: boolean = hasNativeFileTypeMappings()
                     ? isTagParsableFile(uri.fsPath)
                     : isTagParsableFile(uri.fsPath) ||
-                        (ext !== undefined && this.associations_for_did_change?.has(ext.toLowerCase()) === true);
+                    (ext !== undefined && this.associations_for_did_change?.has(ext.toLowerCase()) === true);
                 if (isTrackedFile) {
                     // VS Code has a bug that causes onDidChange events to happen to files that aren't changed,
                     // which causes a large backlog of "files to parse" to accumulate.
@@ -3083,6 +3097,19 @@ export class DefaultClient implements Client {
         }
     }
 
+    public async getTranslationUnitSourceCandidates(uri: vscode.Uri, token: vscode.CancellationToken): Promise<GetTranslationUnitSourceCandidatesResult> {
+        const params: TextDocumentIdentifier = { uri: uri.toString() };
+        await withCancellation(this.ready, token);
+        return DefaultClient.withLspCancellationHandling(
+            () => this.languageClient.sendRequest(GetTranslationUnitSourceCandidatesRequest, params, token), token);
+    }
+
+    public async selectTranslationUnit(uri: vscode.Uri, translationUnit: string): Promise<void> {
+        const params: SelectTranslationUnitParams = { uri: uri.toString(), translationUnit };
+        await this.ready;
+        return this.languageClient.sendNotification(SelectTranslationUnitNotification, params).catch(logAndReturn.undefined);
+    }
+
     public async requestCompiler(newCompilerPath?: string): Promise<configs.CompilerDefaults> {
         const params: QueryDefaultCompilerParams = {
             newTrustedCompilerPath: newCompilerPath ?? ""
@@ -4455,6 +4482,10 @@ class NullClient implements Client {
     takeOwnership(document: vscode.TextDocument): void { }
     sendDidOpen(document: vscode.TextDocument): Promise<void> { return Promise.resolve(); }
     requestSwitchHeaderSource(rootUri: vscode.Uri, fileName: string, token: vscode.CancellationToken): Thenable<string> { return Promise.resolve(""); }
+    getTranslationUnitSourceCandidates(uri: vscode.Uri, token: vscode.CancellationToken): Promise<GetTranslationUnitSourceCandidatesResult> {
+        return Promise.resolve({ candidates: [], currentTranslationUnit: "" });
+    }
+    selectTranslationUnit(uri: vscode.Uri, translationUnit: string): Promise<void> { return Promise.resolve(); }
     updateActiveDocumentTextOptions(): void { }
     didChangeActiveEditor(editor?: vscode.TextEditor): Promise<void> { return Promise.resolve(); }
     restartIntelliSenseForFile(document: vscode.TextDocument): Promise<void> { return Promise.resolve(); }
diff --git a/Extension/src/LanguageServer/extension.ts b/Extension/src/LanguageServer/extension.ts
index 7b20221cf..74c1f3051 100644
--- a/Extension/src/LanguageServer/extension.ts
+++ b/Extension/src/LanguageServer/extension.ts
@@ -383,6 +383,7 @@ export async function registerCommands(enabled: boolean): Promise<void> {
     commandDisposables.forEach(d => d.dispose());
     commandDisposables.length = 0;
     commandDisposables.push(vscode.commands.registerCommand('C_Cpp.SwitchHeaderSource', enabled ? onSwitchHeaderSource : onDisabledCommand));
+    commandDisposables.push(vscode.commands.registerCommand('C_Cpp.SelectTranslationUnit', enabled ? onSelectTranslationUnit : onDisabledCommand));
     commandDisposables.push(vscode.commands.registerCommand('C_Cpp.ResetDatabase', enabled ? onResetDatabase : onDisabledCommand));
     commandDisposables.push(vscode.commands.registerCommand('C_Cpp.SelectIntelliSenseConfiguration', enabled ? selectIntelliSenseConfiguration : onDisabledCommand));
     commandDisposables.push(vscode.commands.registerCommand('C_Cpp.InstallCompiler', enabled ? installCompiler : onDisabledCommand));
@@ -468,6 +469,107 @@ async function onRestartIntelliSenseForFile() {
     return clients.ActiveClient.restartIntelliSenseForFile(activeEditor.document);
 }
 
+function getEditorPath(fileName: string): string {
+    let bestRealRoot: string | undefined;
+    let bestRootPath: string | undefined;
+    clients.forEach(client => {
+        if (!client.RootRealPath) {
+            return;
+        }
+        const relativePath: string = path.relative(client.RootRealPath, fileName);
+        const isUnderRoot: boolean = relativePath === "" ||
+            (relativePath !== ".." && !relativePath.startsWith(`..${path.sep}`) && !path.isAbsolute(relativePath));
+        if (isUnderRoot && (!bestRealRoot || client.RootRealPath.length > bestRealRoot.length)) {
+            bestRealRoot = client.RootRealPath;
+            bestRootPath = client.RootPath;
+        }
+    });
+    return bestRealRoot && bestRootPath ? path.join(bestRootPath, path.relative(bestRealRoot, fileName)) : fileName;
+}
+
+interface TranslationUnitQuickPickItem extends vscode.QuickPickItem {
+    translationUnit: string;
+}
+
+async function onSelectTranslationUnit(): Promise<void> {
+    const activeEditor: vscode.TextEditor | undefined = vscode.window.activeTextEditor;
+    if (!activeEditor || !util.isCpp(activeEditor.document)) {
+        return;
+    }
+
+    const client: Client = clients.ActiveClient;
+    const result = await (async () => {
+        const tokenSource: vscode.CancellationTokenSource = new vscode.CancellationTokenSource();
+        try {
+            const candidatesPromise = client.getTranslationUnitSourceCandidates(activeEditor.document.uri, tokenSource.token);
+            const showProgress: boolean = await new Promise<boolean>((resolve, reject) => {
+                const timer: NodeJS.Timeout = global.setTimeout(() => resolve(true), 2000);
+                void candidatesPromise.then(() => {
+                    clearTimeout(timer);
+                    resolve(false);
+                }, (e) => {
+                    clearTimeout(timer);
+                    reject(e);
+                });
+            });
+
+            if (!showProgress) {
+                return await candidatesPromise;
+            }
+
+            return await vscode.window.withProgress({
+                location: vscode.ProgressLocation.Notification,
+                title: localize('find.translation.units', 'Finding Translation Units...'),
+                cancellable: true
+            }, async (_progress, token) => {
+                const cancellationListener: vscode.Disposable = token.onCancellationRequested(() => tokenSource.cancel());
+                try {
+                    return await candidatesPromise;
+                } finally {
+                    cancellationListener.dispose();
+                }
+            });
+        } catch (e) {
+            if (e instanceof vscode.CancellationError) {
+                return undefined;
+            }
+            throw e;
+        } finally {
+            tokenSource.dispose();
+        }
+    })();
+    if (result === undefined) {
+        return;
+    }
+    if (result.candidates.length === 0) {
+        void vscode.window.showInformationMessage(localize('no.translation.units.found', 'No translation units were found for the active file.'));
+        return;
+    }
+    const currentTranslationUnit: string = getEditorPath(result.currentTranslationUnit);
+    const items: TranslationUnitQuickPickItem[] = result.candidates.map(candidate => {
+        const editorPath: string = getEditorPath(candidate);
+        const relativePath: string = vscode.workspace.asRelativePath(vscode.Uri.file(editorPath));
+        const directory: string = path.dirname(relativePath);
+        const isCurrent: boolean = editorPath === currentTranslationUnit;
+        return {
+            label: `${isCurrent ? "$(check) " : ""}${path.basename(relativePath)}`,
+            description: isCurrent ? localize('current.translation.unit', 'Current translation unit') :
+                directory === "." ? undefined : directory,
+            detail: editorPath,
+            translationUnit: editorPath
+        };
+    });
+    const selection: TranslationUnitQuickPickItem | undefined = await vscode.window.showQuickPick(items, {
+        title: localize('select.translation.unit', 'Select a Translation Unit'),
+        placeHolder: localize('select.translation.unit.placeholder', 'Select a source file to use as the translation unit'),
+        matchOnDescription: true,
+        matchOnDetail: true
+    });
+    if (selection !== undefined) {
+        await client.selectTranslationUnit(activeEditor.document.uri, selection.translationUnit);
+    }
+}
+
 async function onSwitchHeaderSource(): Promise<void> {
     const activeEditor: vscode.TextEditor | undefined = vscode.window.activeTextEditor;
     if (!activeEditor || !util.isCpp(activeEditor.document)) {
@@ -487,16 +589,7 @@ async function onSwitchHeaderSource(): Promise<void> {
             if (!targetFileName) {
                 return;
             }
-            // If the targetFileName has a path that is a symlink target of a workspace folder,
-            // then replace the RootRealPath with the RootPath (the symlink path).
-            let targetFileNameReplaced: boolean = false;
-            clients.forEach(client => {
-                if (!targetFileNameReplaced && client.RootRealPath && client.RootPath !== client.RootRealPath
-                    && targetFileName.startsWith(client.RootRealPath)) {
-                    targetFileName = client.RootPath + targetFileName.substring(client.RootRealPath.length);
-                    targetFileNameReplaced = true;
-                }
-            });
+            targetFileName = getEditorPath(targetFileName);
             const document: vscode.TextDocument = await vscode.workspace.openTextDocument(targetFileName);
             await vscode.window.showTextDocument(document).then(undefined, logAndReturn.undefined);
         } catch (e) {
diff --git a/Extension/src/nativeStrings.json b/Extension/src/nativeStrings.json
index 149887245..ffe091980 100644
--- a/Extension/src/nativeStrings.json
+++ b/Extension/src/nativeStrings.json
@@ -777,5 +777,13 @@
     "browse_database_disabled_incompatible_storage": {
         "text": "The browse database was disabled because its storage location does not support SQLite WAL shared memory. Set browse.databaseFilename to a local path.",
         "hint": "browse.databaseFilename is a setting name. {Locked=\"SQLite WAL\"} {Locked=\"browse.databaseFilename\"}"
+    },
+    "selected_translation_unit_not_include_file_previous": {
+        "text": "The selected translation unit '{0}' does not include '{1}'. IntelliSense will restore the previous translation unit if it is still available; otherwise, it will use '{1}' as a header-only translation unit.",
+        "hint": "{0} is the selected translation unit path. {1} is the active file path. {Locked=\"IntelliSense\"} {Locked=\"{0}\"} {Locked=\"{1}\"}"
+    },
+    "selected_translation_unit_not_include_file_header_only": {
+        "text": "The selected translation unit '{0}' does not include '{1}'. No previous translation unit is available, so IntelliSense will use '{1}' as a header-only translation unit.",
+        "hint": "{0} is the selected translation unit path. {1} is the active file path. {Locked=\"IntelliSense\"} {Locked=\"{0}\"} {Locked=\"{1}\"}"
     }
 }