diff --git a/src/server/session.ts b/src/server/session.ts
index 8d6defa1562..6cd3a7df560 100644
--- a/src/server/session.ts
+++ b/src/server/session.ts
@@ -665,9 +665,8 @@ namespace ts.server {
             if (simplifiedResult) {
                 return this.mapDefinitionInfo(definitions, project);
             }
-            else {
-                return definitions;
-            }
+
+            return definitions.map(Session.mapToOriginalLocation);
         }
 
         private getDefinitionAndBoundSpan(args: protocol.FileLocationRequestArgs, simplifiedResult: boolean): protocol.DefinitionInfoAndBoundSpan | DefinitionInfoAndBoundSpan {
@@ -691,13 +690,30 @@ namespace ts.server {
                 };
             }
 
-            return definitionAndBoundSpan;
+            return {
+                ...definitionAndBoundSpan,
+                definitions: definitionAndBoundSpan.definitions.map(Session.mapToOriginalLocation)
+            };
         }
 
         private mapDefinitionInfo(definitions: ReadonlyArray<DefinitionInfo>, project: Project): ReadonlyArray<protocol.FileSpan> {
             return definitions.map(def => this.toFileSpan(def.fileName, def.textSpan, project));
         }
 
+        private static mapToOriginalLocation<T extends DocumentSpan>(def: T): T {
+            if (def.originalFileName) {
+                Debug.assert(def.originalTextSpan !== undefined, "originalTextSpan should be present if originalFileName is");
+                return {
+                    ...<any>def,
+                    fileName: def.originalFileName,
+                    textSpan: def.originalTextSpan,
+                    targetFileName: def.fileName,
+                    targetTextSpan: def.textSpan
+                };
+            }
+            return def;
+        }
+
         private toFileSpan(fileName: string, textSpan: TextSpan, project: Project): protocol.FileSpan {
             const ls = project.getLanguageService();
             const start = ls.toLineColumnOffset(fileName, textSpan.start);
@@ -732,9 +748,8 @@ namespace ts.server {
             if (simplifiedResult) {
                 return implementations.map(({ fileName, textSpan }) => this.toFileSpan(fileName, textSpan, project));
             }
-            else {
-                return implementations;
-            }
+
+            return implementations.map(Session.mapToOriginalLocation);
         }
 
         private getOccurrences(args: protocol.FileLocationRequestArgs): ReadonlyArray<protocol.OccurrencesResponseItem> {
diff --git a/src/services/services.ts b/src/services/services.ts
index 700b07085a0..401576c57b8 100644
--- a/src/services/services.ts
+++ b/src/services/services.ts
@@ -1634,7 +1634,9 @@ namespace ts {
                 textSpan: {
                     start: newLoc.position,
                     length: info.textSpan.length
-                }
+                },
+                originalFileName: info.fileName,
+                originalTextSpan: info.textSpan
             })
         );
 
@@ -1678,7 +1680,9 @@ namespace ts {
                 textSpan: {
                     start: newLoc.position,
                     length: info.textSpan.length
-                }
+                },
+                originalFileName: info.fileName,
+                originalTextSpan: info.textSpan
             })
         );
 
diff --git a/src/services/types.ts b/src/services/types.ts
index cf2e58a3712..0d15213cb12 100644
--- a/src/services/types.ts
+++ b/src/services/types.ts
@@ -542,6 +542,13 @@ namespace ts {
     export interface DocumentSpan {
         textSpan: TextSpan;
         fileName: string;
+
+        /**
+         * If the span represents a location that was remapped (e.g. via a .d.ts.map file),
+         * then the original filename and span will be specified here
+         */
+        originalTextSpan?: TextSpan;
+        originalFileName?: string;
     }
 
     export interface RenameLocation extends DocumentSpan {
@@ -654,9 +661,7 @@ namespace ts {
         indentMultiLineObjectLiteralBeginningOnBlankLine?: boolean;
     }
 
-    export interface DefinitionInfo {
-        fileName: string;
-        textSpan: TextSpan;
+    export interface DefinitionInfo extends DocumentSpan {
         kind: ScriptElementKind;
         name: string;
         containerKind: ScriptElementKind;