diff --git a/src/server/editorServices.ts b/src/server/editorServices.ts
index 92041c885b2..103590dd381 100644
--- a/src/server/editorServices.ts
+++ b/src/server/editorServices.ts
@@ -3124,19 +3124,24 @@ namespace ts.server {
             return result;
         }
 
-        private collectChanges(lastKnownProjectVersions: protocol.ProjectVersionInfo[], currentProjects: Project[], result: ProjectFilesWithTSDiagnostics[]): void {
+        private collectChanges(
+            lastKnownProjectVersions: protocol.ProjectVersionInfo[],
+            currentProjects: Project[],
+            includeProjectReferenceRedirectInfo: boolean | undefined,
+            result: ProjectFilesWithTSDiagnostics[]
+            ): void {
             for (const proj of currentProjects) {
                 const knownProject = find(lastKnownProjectVersions, p => p.projectName === proj.getProjectName());
-                result.push(proj.getChangesSinceVersion(knownProject && knownProject.version));
+                result.push(proj.getChangesSinceVersion(knownProject && knownProject.version, includeProjectReferenceRedirectInfo));
             }
         }
 
         /* @internal */
-        synchronizeProjectList(knownProjects: protocol.ProjectVersionInfo[]): ProjectFilesWithTSDiagnostics[] {
+        synchronizeProjectList(knownProjects: protocol.ProjectVersionInfo[], includeProjectReferenceRedirectInfo?: boolean): ProjectFilesWithTSDiagnostics[] {
             const files: ProjectFilesWithTSDiagnostics[] = [];
-            this.collectChanges(knownProjects, this.externalProjects, files);
-            this.collectChanges(knownProjects, arrayFrom(this.configuredProjects.values()), files);
-            this.collectChanges(knownProjects, this.inferredProjects, files);
+            this.collectChanges(knownProjects, this.externalProjects, includeProjectReferenceRedirectInfo, files);
+            this.collectChanges(knownProjects, arrayFrom(this.configuredProjects.values()), includeProjectReferenceRedirectInfo, files);
+            this.collectChanges(knownProjects, this.inferredProjects, includeProjectReferenceRedirectInfo, files);
             return files;
         }
 
diff --git a/src/server/project.ts b/src/server/project.ts
index 08c3b7203a3..60f23a7abe0 100644
--- a/src/server/project.ts
+++ b/src/server/project.ts
@@ -167,7 +167,7 @@ namespace ts.server {
         /**
          * Set of files that was returned from the last call to getChangesSinceVersion.
          */
-        private lastReportedFileNames: Map<true> | undefined;
+        private lastReportedFileNames: Map<boolean> | undefined;
         /**
          * Last version that was reported.
          */
@@ -803,6 +803,14 @@ namespace ts.server {
             return result;
         }
 
+        /* @internal */
+        getFileNamesWithRedirectInfo(includeProjectReferenceRedirectInfo: boolean) {
+            return this.getFileNames().map((fileName): protocol.FileWithProjectReferenceRedirectInfo => ({
+                fileName,
+                isSourceOfProjectReferenceRedirect: includeProjectReferenceRedirectInfo && this.isSourceOfProjectReferenceRedirect(fileName)
+             }));
+        }
+
         hasConfigFile(configFilePath: NormalizedPath) {
             if (this.program && this.languageServiceEnabled) {
                 const configFile = this.program.getCompilerOptions().configFile;
@@ -1300,7 +1308,15 @@ namespace ts.server {
         }
 
         /* @internal */
-        getChangesSinceVersion(lastKnownVersion?: number): ProjectFilesWithTSDiagnostics {
+        getChangesSinceVersion(lastKnownVersion?: number, includeProjectReferenceRedirectInfo?: boolean): ProjectFilesWithTSDiagnostics {
+            const includeProjectReferenceRedirectInfoIfRequested =
+                includeProjectReferenceRedirectInfo
+                    ? (files: Map<boolean>) => arrayFrom(files.entries(), ([fileName, isSourceOfProjectReferenceRedirect]): protocol.FileWithProjectReferenceRedirectInfo => ({
+                        fileName,
+                        isSourceOfProjectReferenceRedirect
+                    }))
+                    : (files: Map<boolean>) => arrayFrom(files.keys());
+
             // Update the graph only if initial configured project load is not pending
             if (!this.isInitialLoadPending()) {
                 updateProjectIfDirty(this);
@@ -1324,35 +1340,75 @@ namespace ts.server {
                 }
                 // compute and return the difference
                 const lastReportedFileNames = this.lastReportedFileNames;
-                const externalFiles = this.getExternalFiles().map(f => toNormalizedPath(f));
-                const currentFiles = arrayToSet(this.getFileNames().concat(externalFiles));
+                const externalFiles = this.getExternalFiles().map((f): protocol.FileWithProjectReferenceRedirectInfo => ({
+                    fileName: toNormalizedPath(f),
+                    isSourceOfProjectReferenceRedirect: false
+                }));
+                const currentFiles = arrayToMap(
+                    this.getFileNamesWithRedirectInfo(!!includeProjectReferenceRedirectInfo).concat(externalFiles),
+                    info => info.fileName,
+                    info => info.isSourceOfProjectReferenceRedirect
+                );
+
+                const added: Map<boolean> = new Map<boolean>();
+                const removed: Map<boolean> = new Map<boolean>();
 
-                const added: string[] = [];
-                const removed: string[] = [];
                 const updated: string[] = updatedFileNames ? arrayFrom(updatedFileNames.keys()) : [];
+                const updatedRedirects: protocol.FileWithProjectReferenceRedirectInfo[] = [];
 
-                forEachKey(currentFiles, id => {
-                    if (!lastReportedFileNames.has(id)) {
-                        added.push(id);
+                forEachEntry(currentFiles, (isSourceOfProjectReferenceRedirect, fileName) => {
+                    if (!lastReportedFileNames.has(fileName)) {
+                        added.set(fileName, isSourceOfProjectReferenceRedirect);
+                    }
+                    else if (includeProjectReferenceRedirectInfo && isSourceOfProjectReferenceRedirect !== lastReportedFileNames.get(fileName)){
+                        updatedRedirects.push({
+                            fileName,
+                            isSourceOfProjectReferenceRedirect
+                        });
                     }
                 });
-                forEachKey(lastReportedFileNames, id => {
-                    if (!currentFiles.has(id)) {
-                        removed.push(id);
+                forEachEntry(lastReportedFileNames, (isSourceOfProjectReferenceRedirect, fileName) => {
+                    if (!currentFiles.has(fileName)) {
+                        removed.set(fileName, isSourceOfProjectReferenceRedirect);
                     }
                 });
                 this.lastReportedFileNames = currentFiles;
                 this.lastReportedVersion = this.projectProgramVersion;
-                return { info, changes: { added, removed, updated }, projectErrors: this.getGlobalProjectErrors() };
+                return {
+                    info,
+                    changes: {
+                        added: includeProjectReferenceRedirectInfoIfRequested(added),
+                        removed: includeProjectReferenceRedirectInfoIfRequested(removed),
+                        updated: includeProjectReferenceRedirectInfoIfRequested
+                            ? updated.map((fileName): protocol.FileWithProjectReferenceRedirectInfo => ({
+                                fileName,
+                                isSourceOfProjectReferenceRedirect: this.isSourceOfProjectReferenceRedirect(fileName)
+                            }))
+                            : updated,
+                        updatedRedirects: includeProjectReferenceRedirectInfo ? updatedRedirects : undefined
+                    },
+                    projectErrors: this.getGlobalProjectErrors()
+                };
             }
             else {
                 // unknown version - return everything
-                const projectFileNames = this.getFileNames();
-                const externalFiles = this.getExternalFiles().map(f => toNormalizedPath(f));
+                const projectFileNames = this.getFileNamesWithRedirectInfo(!!includeProjectReferenceRedirectInfo);
+                const externalFiles = this.getExternalFiles().map((f): protocol.FileWithProjectReferenceRedirectInfo => ({
+                    fileName: toNormalizedPath(f),
+                    isSourceOfProjectReferenceRedirect: false
+                }));
                 const allFiles = projectFileNames.concat(externalFiles);
-                this.lastReportedFileNames = arrayToSet(allFiles);
+                this.lastReportedFileNames = arrayToMap(
+                    allFiles,
+                    info => info.fileName,
+                    info => info.isSourceOfProjectReferenceRedirect
+                );
                 this.lastReportedVersion = this.projectProgramVersion;
-                return { info, files: allFiles, projectErrors: this.getGlobalProjectErrors() };
+                return {
+                    info,
+                    files: includeProjectReferenceRedirectInfo ? allFiles : allFiles.map(f => f.fileName),
+                    projectErrors: this.getGlobalProjectErrors()
+                };
             }
         }
 
diff --git a/src/server/protocol.ts b/src/server/protocol.ts
index e44472ed3f0..7f4399842a4 100644
--- a/src/server/protocol.ts
+++ b/src/server/protocol.ts
@@ -1324,6 +1324,18 @@ namespace ts.server.protocol {
         lastFileExceededProgramSize?: string;
     }
 
+    export interface FileWithProjectReferenceRedirectInfo {
+        /**
+         * Name of file
+         */
+        fileName: string;
+
+        /**
+         * True if the file is primarily included in a referenced project
+         */
+        isSourceOfProjectReferenceRedirect: boolean;
+    }
+
     /**
      * Represents a set of changes that happen in project
      */
@@ -1331,15 +1343,20 @@ namespace ts.server.protocol {
         /**
          * List of added files
          */
-        added: string[];
+        added: string[] | FileWithProjectReferenceRedirectInfo[];
         /**
          * List of removed files
          */
-        removed: string[];
+        removed: string[] | FileWithProjectReferenceRedirectInfo[];
         /**
          * List of updated files
          */
-        updated: string[];
+        updated: string[] | FileWithProjectReferenceRedirectInfo[];
+        /**
+         * List of files that have had their project reference redirect status updated
+         * Only provided when the synchronizeProjectList request has includeProjectReferenceRedirectInfo set to true
+         */
+        updatedRedirects?: FileWithProjectReferenceRedirectInfo[];
     }
 
     /**
@@ -1357,8 +1374,10 @@ namespace ts.server.protocol {
         info?: ProjectVersionInfo;
         /**
          * List of files in project (might be omitted if current state of project can be computed using only information from 'changes')
+         * This property will have type FileWithProjectReferenceRedirectInfo[] if includeProjectReferenceRedirectInfo is set to true in
+         * the corresponding SynchronizeProjectList request; otherwise, it will have type string[].
          */
-        files?: string[];
+        files?: string[] | FileWithProjectReferenceRedirectInfo[];
         /**
          * Set of changes in project (omitted if the entire set of files in project should be replaced)
          */
@@ -1621,6 +1640,11 @@ namespace ts.server.protocol {
          * List of last known projects
          */
         knownProjects: ProjectVersionInfo[];
+        /**
+         * If true, response specifies whether or not each file in each project
+         * is a source from a project reference redirect
+         */
+        includeProjectReferenceRedirectInfo?: boolean;
     }
 
     /**
diff --git a/src/server/session.ts b/src/server/session.ts
index 2733ca51412..89231ede007 100644
--- a/src/server/session.ts
+++ b/src/server/session.ts
@@ -2265,7 +2265,7 @@ namespace ts.server {
                 return this.requiredResponse(/*response*/ true);
             },
             [CommandNames.SynchronizeProjectList]: (request: protocol.SynchronizeProjectListRequest) => {
-                const result = this.projectService.synchronizeProjectList(request.arguments.knownProjects);
+                const result = this.projectService.synchronizeProjectList(request.arguments.knownProjects, request.arguments.includeProjectReferenceRedirectInfo);
                 if (!result.some(p => p.projectErrors && p.projectErrors.length !== 0)) {
                     return this.requiredResponse(result);
                 }
diff --git a/src/testRunner/unittests/tsserver/projects.ts b/src/testRunner/unittests/tsserver/projects.ts
index 9fb3da6490e..ae257385268 100644
--- a/src/testRunner/unittests/tsserver/projects.ts
+++ b/src/testRunner/unittests/tsserver/projects.ts
@@ -1431,6 +1431,176 @@ var x = 10;`
             host.checkTimeoutQueueLength(0);
         });
 
+        it("synchronizeProjectList provides redirect info when requested", () => {
+            const projectRootPath = "/users/username/projects/project";
+            const fileA: File = {
+                path: `${projectRootPath}/A/a.ts`,
+                content: "export const foo: string = 5;"
+            };
+            const configA: File = {
+                path: `${projectRootPath}/A/tsconfig.json`,
+                content: `{
+  "compilerOptions": {
+    "composite": true,
+    "declaration": true
+  }
+}`
+            };
+            const fileB: File = {
+                path: `${projectRootPath}/B/b.ts`,
+                content: "import { foo } from \"../A/a\"; console.log(foo);"
+            };
+            const configB: File = {
+                path: `${projectRootPath}/B/tsconfig.json`,
+                content: `{
+  "compilerOptions": {
+    "composite": true,
+    "declaration": true
+  },
+  "references": [
+    { "path": "../A" }
+  ]
+}`
+            };
+            const files = [fileA, fileB, configA, configB, libFile];
+            const host = createServerHost(files);
+            const projectService = createProjectService(host);
+            projectService.openClientFile(fileA.path);
+            projectService.openClientFile(fileB.path);
+            const knownProjects = projectService.synchronizeProjectList([], /*includeProjectReferenceRedirectInfo*/ true);
+            assert.deepEqual(knownProjects[0].files, [
+                {
+                    fileName: libFile.path,
+                    isSourceOfProjectReferenceRedirect: false
+                },
+                {
+                    fileName: fileA.path,
+                    isSourceOfProjectReferenceRedirect: false
+                },
+                {
+                    fileName: configA.path,
+                    isSourceOfProjectReferenceRedirect: false
+                }
+            ]);
+            assert.deepEqual(knownProjects[1].files, [
+                {
+                    fileName: libFile.path,
+                    isSourceOfProjectReferenceRedirect: false
+                },
+                {
+                    fileName: fileA.path,
+                    isSourceOfProjectReferenceRedirect: true,
+                },
+                {
+                    fileName: fileB.path,
+                    isSourceOfProjectReferenceRedirect: false,
+                },
+                {
+                    fileName: configB.path,
+                    isSourceOfProjectReferenceRedirect: false
+                }
+            ]);
+        });
+
+        it("synchronizeProjectList provides updates to redirect info when requested", () => {
+            const projectRootPath = "/users/username/projects/project";
+            const fileA: File = {
+                path: `${projectRootPath}/A/a.ts`,
+                content: "export const foo: string = 5;"
+            };
+            const configA: File = {
+                path: `${projectRootPath}/A/tsconfig.json`,
+                content: `{
+  "compilerOptions": {
+    "composite": true,
+    "declaration": true
+  }
+}`
+            };
+            const fileB: File = {
+                path: `${projectRootPath}/B/b.ts`,
+                content: "import { foo } from \"../B/b2\"; console.log(foo);"
+            };
+            const fileB2: File = {
+                path: `${projectRootPath}/B/b2.ts`,
+                content: "export const foo: string = 5;"
+            };
+            const configB: File = {
+                path: `${projectRootPath}/B/tsconfig.json`,
+                content: `{
+  "compilerOptions": {
+    "composite": true,
+    "declaration": true
+  },
+  "references": [
+    { "path": "../A" }
+  ]
+}`
+            };
+            const files = [fileA, fileB, fileB2, configA, configB, libFile];
+            const host = createServerHost(files);
+            const projectService = createProjectService(host);
+            projectService.openClientFile(fileA.path);
+            projectService.openClientFile(fileB.path);
+            const knownProjects = projectService.synchronizeProjectList([], /*includeProjectReferenceRedirectInfo*/ true);
+            assert.deepEqual(knownProjects[0].files, [
+                {
+                    fileName: libFile.path,
+                    isSourceOfProjectReferenceRedirect: false
+                },
+                {
+                    fileName: fileA.path,
+                    isSourceOfProjectReferenceRedirect: false
+                },
+                {
+                    fileName: configA.path,
+                    isSourceOfProjectReferenceRedirect: false
+                }
+            ]);
+            assert.deepEqual(knownProjects[1].files, [
+                {
+                    fileName: libFile.path,
+                    isSourceOfProjectReferenceRedirect: false
+                },
+                {
+                    fileName: fileB2.path,
+                    isSourceOfProjectReferenceRedirect: false,
+                },
+                {
+                    fileName: fileB.path,
+                    isSourceOfProjectReferenceRedirect: false,
+                },
+                {
+                    fileName: configB.path,
+                    isSourceOfProjectReferenceRedirect: false
+                }
+            ]);
+
+            host.modifyFile(configA.path, `{
+  "compilerOptions": {
+    "composite": true,
+    "declaration": true
+  },
+  "include": [
+      "**/*",
+      "../B/b2.ts"
+  ]
+}`);
+            const newKnownProjects = projectService.synchronizeProjectList(knownProjects.map(proj => proj.info!), /*includeProjectReferenceRedirectInfo*/ true);
+            assert.deepEqual(newKnownProjects[0].changes?.added, [
+                {
+                    fileName: fileB2.path,
+                    isSourceOfProjectReferenceRedirect: false
+                }
+            ]);
+            assert.deepEqual(newKnownProjects[1].changes?.updatedRedirects, [
+                {
+                    fileName: fileB2.path,
+                    isSourceOfProjectReferenceRedirect: true
+                }
+            ]);
+        });
+
         it("handles delayed directory watch invoke on file creation", () => {
             const projectRootPath = "/users/username/projects/project";
             const fileB: File = {
diff --git a/tests/baselines/reference/api/tsserverlibrary.d.ts b/tests/baselines/reference/api/tsserverlibrary.d.ts
index 9a542d064b0..89cc8429f05 100644
--- a/tests/baselines/reference/api/tsserverlibrary.d.ts
+++ b/tests/baselines/reference/api/tsserverlibrary.d.ts
@@ -7066,6 +7066,16 @@ declare namespace ts.server.protocol {
      * compiler settings.
      */
     type ExternalProjectCompilerOptions = CompilerOptions & CompileOnSaveMixin & WatchOptions;
+    interface FileWithProjectReferenceRedirectInfo {
+        /**
+         * Name of file
+         */
+        fileName: string;
+        /**
+         * True if the file is primarily included in a referenced project
+         */
+        isSourceOfProjectReferenceRedirect: boolean;
+    }
     /**
      * Represents a set of changes that happen in project
      */
@@ -7073,15 +7083,20 @@ declare namespace ts.server.protocol {
         /**
          * List of added files
          */
-        added: string[];
+        added: string[] | FileWithProjectReferenceRedirectInfo[];
         /**
          * List of removed files
          */
-        removed: string[];
+        removed: string[] | FileWithProjectReferenceRedirectInfo[];
         /**
          * List of updated files
          */
-        updated: string[];
+        updated: string[] | FileWithProjectReferenceRedirectInfo[];
+        /**
+         * List of files that have had their project reference redirect status updated
+         * Only provided when the synchronizeProjectList request has includeProjectReferenceRedirectInfo set to true
+         */
+        updatedRedirects?: FileWithProjectReferenceRedirectInfo[];
     }
     /**
      * Information found in a configure request.