diff --git a/src/cache/inmemory/inMemoryCache.ts b/src/cache/inmemory/inMemoryCache.ts
index 6aa5c6263d8..50ff65301af 100644
--- a/src/cache/inmemory/inMemoryCache.ts
+++ b/src/cache/inmemory/inMemoryCache.ts
@@ -96,20 +96,15 @@ export class InMemoryCache extends ApolloCache<NormalizedCacheObject> {
       return maybeBroadcastWatch.call(this, c);
     }, {
       makeCacheKey(c: Cache.WatchOptions) {
-        if (c.previousResult) {
-          // If a previousResult was provided, assume the caller would prefer
-          // to compare the previous data to the new data to determine whether
-          // to broadcast, so we should disable caching by returning here, to
-          // give maybeBroadcastWatch a chance to do that comparison.
-          return;
-        }
-
-        if (supportsResultCaching(cache.data)) {
-          // Return a cache key (thus enabling caching) only if we're currently
-          // using a data store that can track cache dependencies.
+        // Return a cache key (thus enabling result caching) only if we're
+        // currently using a data store that can track cache dependencies.
+        const store = c.optimistic ? cache.optimisticData : cache.data;
+        if (supportsResultCaching(store)) {
+          const { optimistic, rootId, variables } = c;
           return cache.cacheKeyRoot.lookup(
             c.query,
-            JSON.stringify(c.variables),
+            store,
+            JSON.stringify({ optimistic, rootId, variables }),
           );
         }
       }
@@ -136,7 +131,6 @@ export class InMemoryCache extends ApolloCache<NormalizedCacheObject> {
       query: options.query,
       variables: options.variables,
       rootId: options.rootId,
-      previousResult: options.previousResult,
       config: this.config,
     }) || null;
   }
@@ -159,7 +153,6 @@ export class InMemoryCache extends ApolloCache<NormalizedCacheObject> {
       query: options.query,
       variables: options.variables,
       returnPartialData: options.returnPartialData,
-      previousResult: options.previousResult,
       config: this.config,
     });
   }
@@ -305,7 +298,6 @@ export class InMemoryCache extends ApolloCache<NormalizedCacheObject> {
       this.diff({
         query: c.query,
         variables: c.variables,
-        previousResult: c.previousResult && c.previousResult(),
         optimistic: c.optimistic,
       }),
     );
diff --git a/src/cache/inmemory/readFromStore.ts b/src/cache/inmemory/readFromStore.ts
index ec26ae65b65..e3f08d148a9 100644
--- a/src/cache/inmemory/readFromStore.ts
+++ b/src/cache/inmemory/readFromStore.ts
@@ -26,7 +26,6 @@ import {
   getMainDefinition,
   getQueryDefinition,
 } from '../../utilities/graphql/getFromAST';
-import { isEqual } from '../../utilities/common/isEqual';
 import { maybeDeepFreeze } from '../../utilities/common/maybeDeepFreeze';
 import { mergeDeepArray } from '../../utilities/common/mergeDeep';
 import { Cache } from '../core/types/Cache';
@@ -141,10 +140,6 @@ export class StoreReader {
    *
    * @param {Object} [variables] A map from the name of a variable to its value. These variables can
    * be referenced by the query document.
-   *
-   * @param {any} previousResult The previous result returned by this function for the same query.
-   * If nothing in the store changed since that previous result then values from the previous result
-   * will be returned to preserve referential equality.
    */
   public readQueryFromStore<QueryType>(
     options: ReadQueryOptions,
@@ -160,14 +155,12 @@ export class StoreReader {
    * identify if any data was missing from the store.
    * @param  {DocumentNode} query A parsed GraphQL query document
    * @param  {Store} store The Apollo Client store object
-   * @param  {any} previousResult The previous result returned by this function for the same query
    * @return {result: Object, complete: [boolean]}
    */
   public diffQueryAgainstStore<T>({
     store,
     query,
     variables,
-    previousResult,
     returnPartialData = true,
     rootId = 'ROOT_QUERY',
     config,
@@ -205,12 +198,6 @@ export class StoreReader {
       });
     }
 
-    if (previousResult) {
-      if (isEqual(previousResult, execResult.result)) {
-        execResult.result = previousResult;
-      }
-    }
-
     return {
       result: execResult.result,
       complete: !hasMissingFields,