Index: lib/Sema/SemaCodeComplete.cpp
===================================================================
--- lib/Sema/SemaCodeComplete.cpp
+++ lib/Sema/SemaCodeComplete.cpp
@@ -954,6 +954,13 @@
 
   // Look through using declarations.
   if (const UsingShadowDecl *Using = dyn_cast<UsingShadowDecl>(R.Declaration)) {
+    // When we are gathering global code completions for caching, the lookup
+    // is performed in the translation unit context which leads to a situation
+    // when a UsingShadowDecl hides a UsingDecl, and nested name specifiers are
+    // then incorrectly applied to the target declaration. This can be avoided
+    // by resetting the declaration that's being hidden.
+    if (Hiding && isa<UsingDecl>(Hiding))
+      Hiding = nullptr;
     AddResult(Result(Using->getTargetDecl(),
                      getBasePriority(Using->getTargetDecl()),
                      R.Qualifier),
Index: test/Index/complete-cached-globals.cpp
===================================================================
--- /dev/null
+++ test/Index/complete-cached-globals.cpp
@@ -0,0 +1,25 @@
+// Note: the run lines follow their respective tests, since line/column
+// matter in this test.
+
+namespace SomeNamespace {
+    class SomeClass {
+    };
+    void SomeFunction();
+}
+
+using SomeNamespace::SomeClass;
+using SomeNamespace::SomeFunction;
+
+static void foo() {
+  return;
+}
+
+// rdar://23454249
+
+// RUN: c-index-test -code-completion-at=%s:14:3 %s | FileCheck -check-prefix=CHECK-CC1 %s
+// RUN: env CINDEXTEST_EDITING=1 CINDEXTEST_COMPLETION_CACHING=1 c-index-test -code-completion-at=%s:14:3 %s | FileCheck -check-prefix=CHECK-CC1 %s
+
+// CHECK-CC1: ClassDecl:{TypedText SomeClass} (50)
+// CHECK-CC1: FunctionDecl:{ResultType void}{TypedText SomeFunction}{LeftParen (}{RightParen )} (50)
+// CHECK-CC1-NOT: {Text SomeNamespace::}{TypedText SomeClass}
+// CHECK-CC1-NOT: {Text SomeNamespace::}{TypedText SomeFunction}