Index: include/clang-c/Index.h
===================================================================
--- include/clang-c/Index.h
+++ include/clang-c/Index.h
@@ -3924,6 +3924,12 @@
  */
 CINDEX_LINKAGE unsigned clang_Cursor_isAnonymous(CXCursor C);
 
+/**
+ * Determine whether the given cursor represents an inline namespace
+ * declaration.
+ */
+CINDEX_LINKAGE unsigned clang_Cursor_isInlineNamespace(CXCursor C);
+
 enum CXRefQualifierKind {
   /** No ref-qualifier was provided. */
   CXRefQualifier_None = 0,
Index: test/Index/print-type.cpp
===================================================================
--- test/Index/print-type.cpp
+++ test/Index/print-type.cpp
@@ -90,6 +90,8 @@
 namespace {
   int a;
 }
+
+inline namespace InlineNS {}
 // RUN: c-index-test -test-print-type %s -std=c++14 | FileCheck %s
 // CHECK: Namespace=outer:1:11 (Definition) [type=] [typekind=Invalid] [isPOD=0]
 // CHECK: ClassTemplate=Foo:4:8 (Definition) [type=] [typekind=Invalid] [isPOD=0]
@@ -204,3 +206,4 @@
 // CHECK: UnionDecl=:86:3 (Definition) [type=X::(anonymous union at {{.*}}print-type.cpp:86:3)] [typekind=Record] [isPOD=1] [nbFields=2] [isAnon=1]
 // CHECK: EnumDecl=:87:3 (Definition) [type=X::(anonymous enum at {{.*}}print-type.cpp:87:3)] [typekind=Enum] [isPOD=1] [isAnon=1]
 // CHECK: Namespace=:90:11 (Definition) [type=] [typekind=Invalid] [isPOD=0] [isAnon=1]
+// CHECK: Namespace=InlineNS:94:18 (Definition) [type=] [typekind=Invalid] [isPOD=0] [isInlineNamespace=1]
Index: tools/libclang/CXType.cpp
===================================================================
--- tools/libclang/CXType.cpp
+++ tools/libclang/CXType.cpp
@@ -1245,6 +1245,15 @@
 
   return 0;
 }
+
+unsigned clang_Cursor_isInlineNamespace(CXCursor C) {
+  if (!clang_isDeclaration(C.kind))
+    return 0;
+  const Decl *D = cxcursor::getCursorDecl(C);
+  const NamespaceDecl *ND = dyn_cast_or_null<NamespaceDecl>(D);
+  return ND ? ND->isInline() : 0;
+}
+
 CXType clang_Type_getNamedType(CXType CT){
   QualType T = GetQualType(CT);
   const Type *TP = T.getTypePtrOrNull();