diff --git a/package.json b/package.json
index b7ced4bda..450f76801 100644
--- a/package.json
+++ b/package.json
@@ -2358,6 +2358,7 @@
 		"@vscode/extension-telemetry": "0.7.5",
 		"apollo-boost": "^0.4.9",
 		"apollo-link-context": "1.0.20",
+		"cockatiel": "^3.1.1",
 		"cross-fetch": "3.1.5",
 		"dayjs": "1.10.4",
 		"events": "3.2.0",
diff --git a/src/github/loggingOctokit.ts b/src/github/loggingOctokit.ts
index 3e19e3fbd..4c6808d6f 100644
--- a/src/github/loggingOctokit.ts
+++ b/src/github/loggingOctokit.ts
@@ -5,6 +5,8 @@
 
 import { Octokit } from '@octokit/rest';
 import { ApolloClient, ApolloQueryResult, FetchResult, MutationOptions, NormalizedCacheObject, OperationVariables, QueryOptions } from 'apollo-boost';
+import { bulkhead, BulkheadPolicy } from 'cockatiel';
+import * as vscode from 'vscode';
 import Logger from '../common/logger';
 import { ITelemetry } from '../common/telemetry';
 import { RateLimit } from './graphql';
@@ -17,11 +19,27 @@ interface RestResponse {
 }
 
 export class RateLogger {
+	private bulkhead: BulkheadPolicy = bulkhead(140);
 	private static ID = 'RateLimit';
 	private hasLoggedLowRateLimit: boolean = false;
 
 	constructor(private readonly telemetry: ITelemetry) { }
 
+	public logAndLimit(apiRequest: () => Promise<any>): Promise<any> | undefined {
+		if (this.bulkhead.executionSlots === 0) {
+			Logger.error('API call count has exceeded 140 concurrent calls.', RateLogger.ID);
+			// We have hit more than 140 concurrent API requests.
+			/* __GDPR__
+				"pr.highApiCallRate" : {}
+			*/
+			this.telemetry.sendTelemetryErrorEvent('pr.highApiCallRate');
+			vscode.window.showErrorMessage(vscode.l10n.t('The GitHub Pull Requests extension is making too many requests to GitHub. This indicates a bug in the extension. Please file an issue on GitHub and include the output from "GitHub Pull Request".'));
+			return undefined;
+		}
+		Logger.debug(`Extension rate limit remaining: ${this.bulkhead.executionSlots}`, RateLogger.ID);
+		return this.bulkhead.execute(() => apiRequest());
+	}
+
 	public async logRateLimit(info: string | undefined, result: Promise<{ data: { rateLimit: RateLimit | undefined } | undefined } | undefined>, isRest: boolean = false) {
 		let rateLimitInfo;
 		try {
@@ -70,13 +88,19 @@ export class LoggingApolloClient {
 	constructor(private readonly _graphql: ApolloClient<NormalizedCacheObject>, private _rateLogger: RateLogger) { };
 
 	query<T = any, TVariables = OperationVariables>(options: QueryOptions<TVariables>): Promise<ApolloQueryResult<T>> {
-		const result = this._graphql.query(options);
+		const result = this._rateLogger.logAndLimit(() => this._graphql.query(options));
+		if (result === undefined) {
+			throw new Error('API call count has exceeded a rate limit.');
+		}
 		this._rateLogger.logRateLimit((options.query.definitions[0] as { name: { value: string } | undefined }).name?.value, result as any);
 		return result;
 	}
 
 	mutate<T = any, TVariables = OperationVariables>(options: MutationOptions<T, TVariables>): Promise<FetchResult<T>> {
-		const result = this._graphql.mutate(options);
+		const result = this._rateLogger.logAndLimit(() => this._graphql.mutate(options));
+		if (result === undefined) {
+			throw new Error('API call count has exceeded a rate limit.');
+		}
 		this._rateLogger.logRateLimit(options.context, result as any);
 		return result;
 	}
@@ -86,7 +110,10 @@ export class LoggingOctokit {
 	constructor(public readonly api: Octokit, private _rateLogger: RateLogger) { };
 
 	async call<T, U>(api: (T) => Promise<U>, args: T): Promise<U> {
-		const result = api(args);
+		const result = this._rateLogger.logAndLimit(() => api(args));
+		if (result === undefined) {
+			throw new Error('API call count has exceeded a rate limit.');
+		}
 		this._rateLogger.logRestRateLimit((api as unknown as { endpoint: { DEFAULTS: { url: string } | undefined } | undefined }).endpoint?.DEFAULTS?.url, result as Promise<unknown> as Promise<RestResponse>);
 		return result;
 	}
diff --git a/yarn.lock b/yarn.lock
index 06e179dab..f9a4aa9d4 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1693,6 +1693,11 @@ co@^4.6.0:
   resolved "https://registry.yarnpkg.com/co/-/co-4.6.0.tgz#6ea6bdf3d853ae54ccb8e47bfa0bf3f9031fb184"
   integrity sha1-bqa989hTrlTMuOR7+gvz+QMfsYQ=
 
+cockatiel@^3.1.1:
+  version "3.1.1"
+  resolved "https://registry.yarnpkg.com/cockatiel/-/cockatiel-3.1.1.tgz#82c95dcad673649c43c0a35c424c5d2ad59d4e6b"
+  integrity sha512-zHMqBGvkZLfMKkBMD+0U8X1nW8zYwMtymgJ8CTknWOmTDpvjEwygtFN4QR9A1iFQDwCbg8g8+B/zVBoxvj1feQ==
+
 color-convert@^1.9.0:
   version "1.9.3"
   resolved "https://registry.yarnpkg.com/color-convert/-/color-convert-1.9.3.tgz#bb71850690e1f136567de629d2d5471deda4c1e8"