diff --git a/src/vs/vscode.proposed.d.ts b/src/vs/vscode.proposed.d.ts
index 18776fcaae2..9d2e814577c 100644
--- a/src/vs/vscode.proposed.d.ts
+++ b/src/vs/vscode.proposed.d.ts
@@ -209,6 +209,12 @@ declare module 'vscode' {
 		 * The maximum number of results to be returned.
 		 */
 		maxResults?: number;
+
+		/**
+		 * A CancellationToken that represents the session for this search query. If the provider chooses to, this object can be used as the key for a cache,
+		 * and searches with the same session object can search the same cache. When the token is cancelled, the session is complete and the cache can be cleared.
+		 */
+		session?: CancellationToken;
 	}
 
 	/**
diff --git a/src/vs/workbench/api/node/extHostSearch.fileIndex.ts b/src/vs/workbench/api/node/extHostSearch.fileIndex.ts
index c59b1ab89e0..b8a6a502d77 100644
--- a/src/vs/workbench/api/node/extHostSearch.fileIndex.ts
+++ b/src/vs/workbench/api/node/extHostSearch.fileIndex.ts
@@ -552,9 +552,9 @@ export class FileIndexSearchManager {
 		});
 	}
 
-	public clearCache(cacheKey: string): Promise<void> {
+	public clearCache(cacheKey: string): void {
 		if (!this.folderCacheKeys.has(cacheKey)) {
-			return Promise.resolve(undefined);
+			return undefined;
 		}
 
 		const expandedKeys = this.folderCacheKeys.get(cacheKey);
@@ -562,7 +562,7 @@ export class FileIndexSearchManager {
 
 		this.folderCacheKeys.delete(cacheKey);
 
-		return Promise.resolve(undefined);
+		return undefined;
 	}
 
 	private preventCancellation<C>(promise: CancelablePromise<C>): CancelablePromise<C> {
diff --git a/src/vs/workbench/api/node/extHostSearch.ts b/src/vs/workbench/api/node/extHostSearch.ts
index cf20b24f285..a06729009c6 100644
--- a/src/vs/workbench/api/node/extHostSearch.ts
+++ b/src/vs/workbench/api/node/extHostSearch.ts
@@ -158,9 +158,10 @@ export class ExtHostSearch implements ExtHostSearchShape {
 			this._internalFileSearchProvider.clearCache(cacheKey);
 		}
 
-		// Actually called once per provider.
-		// Only relevant to file index search.
-		return this._fileIndexSearchManager.clearCache(cacheKey);
+		this._fileSearchManager.clearCache(cacheKey);
+		this._fileIndexSearchManager.clearCache(cacheKey);
+
+		return Promise.resolve(undefined);
 	}
 
 	$provideTextSearchResults(handle: number, session: number, rawQuery: IRawTextQuery, token: CancellationToken): Thenable<ISearchCompleteStats> {
diff --git a/src/vs/workbench/services/search/node/fileSearchManager.ts b/src/vs/workbench/services/search/node/fileSearchManager.ts
index 2713a180fb3..39fd6f33ef6 100644
--- a/src/vs/workbench/services/search/node/fileSearchManager.ts
+++ b/src/vs/workbench/services/search/node/fileSearchManager.ts
@@ -47,7 +47,7 @@ class FileSearchEngine {
 
 	private globalExcludePattern?: glob.ParsedExpression;
 
-	constructor(private config: IFileQuery, private provider: vscode.FileSearchProvider) {
+	constructor(private config: IFileQuery, private provider: vscode.FileSearchProvider, private sessionToken?: CancellationToken) {
 		this.filePattern = config.filePattern;
 		this.includePattern = config.includePattern && glob.parse(config.includePattern);
 		this.maxResults = config.maxResults || undefined;
@@ -107,7 +107,7 @@ class FileSearchEngine {
 	}
 
 	private searchInFolder(fq: IFolderQuery<URI>, onResult: (match: IInternalFileMatch) => void): Promise<IFileSearchProviderStats | null> {
-		let cancellation = new CancellationTokenSource();
+		const cancellation = new CancellationTokenSource();
 		return new Promise((resolve, reject) => {
 			const options = this.getSearchOptionsForFolder(fq);
 			const tree = this.initDirectoryTree();
@@ -185,7 +185,8 @@ class FileSearchEngine {
 			useIgnoreFiles: !fq.disregardIgnoreFiles,
 			useGlobalIgnoreFiles: !fq.disregardGlobalIgnoreFiles,
 			followSymlinks: !fq.ignoreSymlinks,
-			maxResults: this.config.maxResults
+			maxResults: this.config.maxResults,
+			session: this.sessionToken
 		};
 	}
 
@@ -282,8 +283,11 @@ export class FileSearchManager {
 
 	private static readonly BATCH_SIZE = 512;
 
+	private readonly sessions = new Map<string, CancellationTokenSource>();
+
 	fileSearch(config: IFileQuery, provider: vscode.FileSearchProvider, onBatch: (matches: IFileMatch[]) => void, token: CancellationToken): Promise<ISearchCompleteStats> {
-		const engine = new FileSearchEngine(config, provider);
+		const sessionTokenSource = this.getSessionTokenSource(config.cacheKey);
+		const engine = new FileSearchEngine(config, provider, sessionTokenSource && sessionTokenSource.token);
 
 		let resultCount = 0;
 		const onInternalResult = (batch: IInternalFileMatch[]) => {
@@ -305,6 +309,25 @@ export class FileSearchManager {
 			});
 	}
 
+	clearCache(cacheKey: string): void {
+		const sessionTokenSource = this.getSessionTokenSource(cacheKey);
+		if (sessionTokenSource) {
+			sessionTokenSource.cancel();
+		}
+	}
+
+	private getSessionTokenSource(cacheKey: string | undefined): CancellationTokenSource | undefined {
+		if (!cacheKey) {
+			return undefined;
+		}
+
+		if (!this.sessions.has(cacheKey)) {
+			this.sessions.set(cacheKey, new CancellationTokenSource());
+		}
+
+		return this.sessions.get(cacheKey);
+	}
+
 	private rawMatchToSearchItem(match: IInternalFileMatch): IFileMatch {
 		if (match.relativePath) {
 			return {
diff --git a/src/vs/workbench/services/search/node/searchService.ts b/src/vs/workbench/services/search/node/searchService.ts
index 0c6db0e6d25..2cb88eddd97 100644
--- a/src/vs/workbench/services/search/node/searchService.ts
+++ b/src/vs/workbench/services/search/node/searchService.ts
@@ -441,7 +441,8 @@ export class SearchService extends Disposable implements ISearchService {
 	public clearCache(cacheKey: string): Promise<void> {
 		const clearPs = [
 			this.diskSearch,
-			...values(this.fileIndexProviders)
+			...values(this.fileIndexProviders),
+			...values(this.fileSearchProviders)
 		].map(provider => provider && provider.clearCache(cacheKey));
 
 		return Promise.all(clearPs)