diff --git a/clang/include/clang-c/Index.h b/clang/include/clang-c/Index.h
index c50ac1b6d248..bb2cbe30e3a3 100644
--- a/clang/include/clang-c/Index.h
+++ b/clang/include/clang-c/Index.h
@@ -32,7 +32,7 @@
  * compatible, thus CINDEX_VERSION_MAJOR is expected to remain stable.
  */
 #define CINDEX_VERSION_MAJOR 0
-#define CINDEX_VERSION_MINOR 38
+#define CINDEX_VERSION_MINOR 39
 
 #define CINDEX_VERSION_ENCODE(major, minor) ( \
       ((major) * 10000)                       \
@@ -4080,6 +4080,23 @@ CINDEX_LINKAGE unsigned clang_Cursor_isObjCOptional(CXCursor C);
  */
 CINDEX_LINKAGE unsigned clang_Cursor_isVariadic(CXCursor C);
 
+/**
+ * \brief Returns non-zero if the given cursor points to a symbol marked with
+ * external_source_symbol attribute.
+ *
+ * \param language If non-NULL, and the attribute is present, will be set to
+ * the 'language' string from the attribute.
+ *
+ * \param definedIn If non-NULL, and the attribute is present, will be set to
+ * the 'definedIn' string from the attribute.
+ *
+ * \param isGenerated If non-NULL, and the attribute is present, will be set to
+ * non-zero is the 'generated_declaration' is set in the attribute.
+ */
+CINDEX_LINKAGE unsigned clang_Cursor_isExternalSymbol(CXCursor C,
+                                       CXString *language, CXString *definedIn,
+                                       unsigned *isGenerated);
+
 /**
  * \brief Given a cursor that represents a declaration, return the associated
  * comment's source range.  The range may include multiple consecutive comments
diff --git a/clang/test/Index/get-cursor.m b/clang/test/Index/get-cursor.m
index af277d45fdf4..e85d49fb0c3e 100644
--- a/clang/test/Index/get-cursor.m
+++ b/clang/test/Index/get-cursor.m
@@ -154,6 +154,12 @@ SomeT someVar;
 typedef MY_TYPE2(SomeT2) { int x; };
 SomeT2 someVar2;
 
+#define GEN_DECL(mod_name) __attribute__((external_source_symbol(language="Swift", defined_in=mod_name, generated_declaration)))
+
+GEN_DECL("some_module")
+@interface ExtCls
+-(void)method;
+@end
 
 // RUN: c-index-test -cursor-at=%s:4:28 -cursor-at=%s:5:28 %s | FileCheck -check-prefix=CHECK-PROP %s
 // CHECK-PROP: ObjCPropertyDecl=foo1:4:26
@@ -226,3 +232,8 @@ SomeT2 someVar2;
 // CHECK-TRANSPARENT: 147:1 TypeRef=TokenPaste_t:144:9 Extent=[147:1 - 147:13] Spelling=TokenPaste_t ([147:1 - 147:13])
 // CHECK-TRANSPARENT: 151:1 TypeRef=SomeT:150:17 (Transparent: struct SomeT) Extent=[151:1 - 151:6] Spelling=SomeT ([151:1 - 151:6])
 // CHECK-TRANSPARENT: 155:1 TypeRef=SomeT2:154:18 Extent=[155:1 - 155:7] Spelling=SomeT2 ([155:1 - 155:7])
+
+// RUN: c-index-test -cursor-at=%s:160:12 -cursor-at=%s:161:8 %s | FileCheck -check-prefix=CHECK-EXTERNAL %s
+// CHECK-EXTERNAL: 160:12 ObjCInterfaceDecl=ExtCls:160:12 (external lang: Swift, defined: some_module, gen: 1)
+// CHECK-EXTERNAL: 161:8 ObjCInstanceMethodDecl=method:161:8 (external lang: Swift, defined: some_module, gen: 1)
+C
\ No newline at end of file
diff --git a/clang/tools/c-index-test/c-index-test.c b/clang/tools/c-index-test/c-index-test.c
index 1179fbf39113..1f5d60443197 100644
--- a/clang/tools/c-index-test/c-index-test.c
+++ b/clang/tools/c-index-test/c-index-test.c
@@ -809,6 +809,19 @@ static void PrintCursor(CXCursor Cursor, const char *CommentSchemaFile) {
     if (clang_Cursor_isObjCOptional(Cursor))
       printf(" (@optional)");
 
+    {
+      CXString language;
+      CXString definedIn;
+      unsigned generated;
+      if (clang_Cursor_isExternalSymbol(Cursor, &language, &definedIn,
+                                        &generated)) {
+        printf(" (external lang: %s, defined: %s, gen: %d)",
+            clang_getCString(language), clang_getCString(definedIn), generated);
+        clang_disposeString(language);
+        clang_disposeString(definedIn);
+      }
+    }
+
     if (Cursor.kind == CXCursor_IBOutletCollectionAttr) {
       CXType T =
         clang_getCanonicalType(clang_getIBOutletCollectionType(Cursor));
diff --git a/clang/tools/libclang/CIndex.cpp b/clang/tools/libclang/CIndex.cpp
index c251d83e2097..9c795ae9c5b7 100644
--- a/clang/tools/libclang/CIndex.cpp
+++ b/clang/tools/libclang/CIndex.cpp
@@ -7479,6 +7479,35 @@ unsigned clang_Cursor_isVariadic(CXCursor C) {
   return 0;
 }
 
+unsigned clang_Cursor_isExternalSymbol(CXCursor C,
+                                     CXString *language, CXString *definedIn,
+                                     unsigned *isGenerated) {
+  if (!clang_isDeclaration(C.kind))
+    return 0;
+
+  const Decl *D = getCursorDecl(C);
+
+  auto getExternalSymAttr = [](const Decl *D) -> ExternalSourceSymbolAttr* {
+    if (auto *attr = D->getAttr<ExternalSourceSymbolAttr>())
+      return attr;
+    if (auto *dcd = dyn_cast<Decl>(D->getDeclContext())) {
+      if (auto *attr = dcd->getAttr<ExternalSourceSymbolAttr>())
+        return attr;
+    }
+    return nullptr;
+  };
+  if (auto *attr = getExternalSymAttr(D)) {
+    if (language)
+      *language = cxstring::createDup(attr->getLanguage());
+    if (definedIn)
+      *definedIn = cxstring::createDup(attr->getDefinedIn());
+    if (isGenerated)
+      *isGenerated = attr->getGeneratedDeclaration();
+    return 1;
+  }
+  return 0;
+}
+
 CXSourceRange clang_Cursor_getCommentRange(CXCursor C) {
   if (!clang_isDeclaration(C.kind))
     return clang_getNullRange();
diff --git a/clang/tools/libclang/libclang.exports b/clang/tools/libclang/libclang.exports
index 895dd804b008..d9a406e5741b 100644
--- a/clang/tools/libclang/libclang.exports
+++ b/clang/tools/libclang/libclang.exports
@@ -35,6 +35,7 @@ clang_Cursor_getReceiverType
 clang_Cursor_isAnonymous
 clang_Cursor_isBitField
 clang_Cursor_isDynamicCall
+clang_Cursor_isExternalSymbol
 clang_Cursor_isNull
 clang_Cursor_isObjCOptional
 clang_Cursor_isVariadic