Index: include/clang-c/Index.h
===================================================================
--- include/clang-c/Index.h
+++ 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 56
+#define CINDEX_VERSION_MINOR 57
 
 #define CINDEX_VERSION_ENCODE(major, minor) ( \
       ((major) * 10000)                       \
@@ -3932,6 +3932,12 @@
  */
 CINDEX_LINKAGE unsigned clang_Cursor_isAnonymousRecordDecl(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] [isAnonRecDecl=0] [isInlineNamespace=1]
Index: tools/c-index-test/c-index-test.c
===================================================================
--- tools/c-index-test/c-index-test.c
+++ tools/c-index-test/c-index-test.c
@@ -1671,6 +1671,13 @@
       printf(" [isAnonRecDecl=%d]", isAnonRecDecl);
     }
 
+    /* Print if it is an inline namespace decl */
+    {
+      unsigned isInlineNamespace = clang_Cursor_isInlineNamespace(cursor);
+      if (isInlineNamespace != 0)
+        printf(" [isInlineNamespace=%d]", isInlineNamespace);
+    }
+
     printf("\n");
   }
   return CXChildVisit_Recurse;
Index: tools/libclang/CXType.cpp
===================================================================
--- tools/libclang/CXType.cpp
+++ tools/libclang/CXType.cpp
@@ -1263,6 +1263,14 @@
   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();
Index: tools/libclang/libclang.exports
===================================================================
--- tools/libclang/libclang.exports
+++ tools/libclang/libclang.exports
@@ -43,6 +43,7 @@
 clang_Cursor_isBitField
 clang_Cursor_isDynamicCall
 clang_Cursor_isExternalSymbol
+clang_Cursor_isInlineNamespace
 clang_Cursor_isNull
 clang_Cursor_isObjCOptional
 clang_Cursor_isVariadic