Index: cfe/trunk/docs/ReleaseNotes.rst
===================================================================
--- cfe/trunk/docs/ReleaseNotes.rst
+++ cfe/trunk/docs/ReleaseNotes.rst
@@ -94,6 +94,9 @@
 Attribute Changes in Clang
 --------------------------
 
+- The presence of __attribute__((availability(...))) on a declaration no longer
+  implies default visibility for that declaration on macOS.
+
 - ...
 
 Windows Support
Index: cfe/trunk/lib/AST/Decl.cpp
===================================================================
--- cfe/trunk/lib/AST/Decl.cpp
+++ cfe/trunk/lib/AST/Decl.cpp
@@ -216,14 +216,6 @@
     return getVisibilityFromAttr(A);
   }
 
-  // If we're on Mac OS X, an 'availability' for Mac OS X attribute
-  // implies visibility(default).
-  if (D->getASTContext().getTargetInfo().getTriple().isOSDarwin()) {
-    for (const auto *A : D->specific_attrs<AvailabilityAttr>())
-      if (A->getPlatform()->getName().equals("macos"))
-        return DefaultVisibility;
-  }
-
   return None;
 }
 
Index: cfe/trunk/test/CodeGen/attr-availability.c
===================================================================
--- cfe/trunk/test/CodeGen/attr-availability.c
+++ cfe/trunk/test/CodeGen/attr-availability.c
@@ -8,9 +8,9 @@
 void f2();
 void f2() { }
 
-// CHECK-10_4-LABEL: define void @f3
-// CHECK-10_5-LABEL: define void @f3
-// CHECK-10_6-LABEL: define void @f3
+// CHECK-10_4-LABEL: define hidden void @f3
+// CHECK-10_5-LABEL: define hidden void @f3
+// CHECK-10_6-LABEL: define hidden void @f3
 void f3() __attribute__((availability(macosx,introduced=10.5)));
 void f3() { }