diff --git a/libc/include/bits/fortify/string.h b/libc/include/bits/fortify/string.h
index 600ef14..4a7ed12 100644
--- a/libc/include/bits/fortify/string.h
+++ b/libc/include/bits/fortify/string.h
@@ -45,21 +45,13 @@
 __BIONIC_FORTIFY_INLINE
 void* memcpy(void* const dst __pass_object_size0, const void* src, size_t copy_amount)
         __overloadable {
-    size_t bos_dst = __bos0(dst);
-    if (__bos_trivially_ge(bos_dst, copy_amount)) {
-        return __builtin_memcpy(dst, src, copy_amount);
-    }
-    return __builtin___memcpy_chk(dst, src, copy_amount, bos_dst);
+    return __builtin___memcpy_chk(dst, src, copy_amount, __bos0(dst));
 }
 
 /* No diag -- clang diagnoses misuses of this on its own.  */
 __BIONIC_FORTIFY_INLINE
 void* memmove(void* const dst __pass_object_size0, const void* src, size_t len) __overloadable {
-    size_t bos_dst = __bos0(dst);
-    if (__bos_trivially_ge(bos_dst, len)) {
-        return __builtin_memmove(dst, src, len);
-    }
-    return __builtin___memmove_chk(dst, src, len, bos_dst);
+    return __builtin___memmove_chk(dst, src, len, __bos0(dst));
 }
 #endif
 
@@ -87,12 +79,10 @@
         __clang_error_if(__bos_unevaluated_le(__bos(dst), __builtin_strlen(src)),
                          "'stpcpy' called with string bigger than buffer") {
 #if __ANDROID_API__ >= 21 && __BIONIC_FORTIFY_RUNTIME_CHECKS_ENABLED
-    size_t bos_dst = __bos(dst);
-    if (!__bos_trivially_gt(bos_dst, __builtin_strlen(src))) {
-        return __builtin___stpcpy_chk(dst, src, bos_dst);
-    }
-#endif
+    return __builtin___stpcpy_chk(dst, src, __bos(dst));
+#else
     return __builtin_stpcpy(dst, src);
+#endif
 }
 
 __BIONIC_FORTIFY_INLINE
@@ -101,12 +91,10 @@
         __clang_error_if(__bos_unevaluated_le(__bos(dst), __builtin_strlen(src)),
                          "'strcpy' called with string bigger than buffer") {
 #if __ANDROID_API__ >= 17 && __BIONIC_FORTIFY_RUNTIME_CHECKS_ENABLED
-    size_t bos_dst = __bos(dst);
-    if (!__bos_trivially_gt(bos_dst, __builtin_strlen(src))) {
-        return __builtin___strcpy_chk(dst, src, bos_dst);
-    }
-#endif
+    return __builtin___strcpy_chk(dst, src, __bos(dst));
+#else
     return __builtin_strcpy(dst, src);
+#endif
 }
 
 __BIONIC_FORTIFY_INLINE
@@ -135,12 +123,10 @@
         /* If you're a user who wants this warning to go away: use `(&memset)(foo, bar, baz)`. */
         __clang_warning_if(c && !n, "'memset' will set 0 bytes; maybe the arguments got flipped?") {
 #if __ANDROID_API__ >= 17 && __BIONIC_FORTIFY_RUNTIME_CHECKS_ENABLED
-    size_t bos = __bos0(s);
-    if (!__bos_trivially_ge(bos, n)) {
-        return __builtin___memset_chk(s, c, n, bos);
-    }
-#endif
+    return __builtin___memset_chk(s, c, n, __bos0(s));
+#else
     return __builtin_memset(s, c, n);
+#endif
 }
 
 #if __ANDROID_API__ >= 23 && __BIONIC_FORTIFY_RUNTIME_CHECKS_ENABLED
@@ -205,13 +191,10 @@
         __clang_error_if(__bos_unevaluated_lt(__bos(dst), size),
                          "'strlcpy' called with size bigger than buffer") {
 #if __ANDROID_API__ >= 17 && __BIONIC_FORTIFY_RUNTIME_CHECKS_ENABLED
-    size_t bos = __bos(dst);
-
-    if (bos != __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __strlcpy_chk(dst, src, size, bos);
-    }
-#endif
+    return __strlcpy_chk(dst, src, size, __bos(dst));
+#else
     return __call_bypassing_fortify(strlcpy)(dst, src, size);
+#endif
 }
 
 __BIONIC_FORTIFY_INLINE
@@ -220,11 +203,7 @@
         __clang_error_if(__bos_unevaluated_lt(__bos(dst), size),
                          "'strlcat' called with size bigger than buffer") {
 #if __ANDROID_API__ >= 17 && __BIONIC_FORTIFY_RUNTIME_CHECKS_ENABLED
-    size_t bos = __bos(dst);
-
-    if (bos != __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __strlcat_chk(dst, src, size, bos);
-    }
+    return __strlcat_chk(dst, src, size, __bos(dst));
 #endif
     return __call_bypassing_fortify(strlcat)(dst, src, size);
 }
diff --git a/linker/linker.cpp b/linker/linker.cpp
index 8de82d5..5d38151 100644
--- a/linker/linker.cpp
+++ b/linker/linker.cpp
@@ -724,12 +724,12 @@
 }
 
 
-static const ElfW(Sym)* dlsym_handle_lookup(android_namespace_t* ns,
-                                            soinfo* root,
-                                            soinfo* skip_until,
-                                            soinfo** found,
-                                            SymbolName& symbol_name,
-                                            const version_info* vi) {
+static const ElfW(Sym)* dlsym_handle_lookup_impl(android_namespace_t* ns,
+                                                 soinfo* root,
+                                                 soinfo* skip_until,
+                                                 soinfo** found,
+                                                 SymbolName& symbol_name,
+                                                 const version_info* vi) {
   const ElfW(Sym)* result = nullptr;
   bool skip_lookup = skip_until != nullptr;
 
@@ -755,38 +755,6 @@
   return result;
 }
 
-static const ElfW(Sym)* dlsym_linear_lookup(android_namespace_t* ns,
-                                            const char* name,
-                                            const version_info* vi,
-                                            soinfo** found,
-                                            soinfo* caller,
-                                            void* handle);
-
-// This is used by dlsym(3).  It performs symbol lookup only within the
-// specified soinfo object and its dependencies in breadth first order.
-static const ElfW(Sym)* dlsym_handle_lookup(soinfo* si,
-                                            soinfo** found,
-                                            const char* name,
-                                            const version_info* vi) {
-  // According to man dlopen(3) and posix docs in the case when si is handle
-  // of the main executable we need to search not only in the executable and its
-  // dependencies but also in all libraries loaded with RTLD_GLOBAL.
-  //
-  // Since RTLD_GLOBAL is always set for the main executable and all dt_needed shared
-  // libraries and they are loaded in breath-first (correct) order we can just execute
-  // dlsym(RTLD_DEFAULT, ...); instead of doing two stage lookup.
-  if (si == solist_get_somain()) {
-    return dlsym_linear_lookup(&g_default_namespace, name, vi, found, nullptr, RTLD_DEFAULT);
-  }
-
-  SymbolName symbol_name(name);
-  // note that the namespace is not the namespace associated with caller_addr
-  // we use ns associated with root si intentionally here. Using caller_ns
-  // causes problems when user uses dlopen_ext to open a library in the separate
-  // namespace and then calls dlsym() on the handle.
-  return dlsym_handle_lookup(si->get_primary_namespace(), si, nullptr, found, symbol_name, vi);
-}
-
 /* This is used by dlsym(3) to performs a global symbol lookup. If the
    start value is null (for RTLD_DEFAULT), the search starts at the
    beginning of the global solist. Otherwise the search starts at the
@@ -830,16 +798,16 @@
     }
   }
 
-  // If not found - use dlsym_handle_lookup for caller's local_group
+  // If not found - use dlsym_handle_lookup_impl for caller's local_group
   if (s == nullptr && caller != nullptr) {
     soinfo* local_group_root = caller->get_local_group_root();
 
-    return dlsym_handle_lookup(local_group_root->get_primary_namespace(),
-                               local_group_root,
-                               (handle == RTLD_NEXT) ? caller : nullptr,
-                               found,
-                               symbol_name,
-                               vi);
+    return dlsym_handle_lookup_impl(local_group_root->get_primary_namespace(),
+                                    local_group_root,
+                                    (handle == RTLD_NEXT) ? caller : nullptr,
+                                    found,
+                                    symbol_name,
+                                    vi);
   }
 
   if (s != nullptr) {
@@ -850,6 +818,31 @@
   return s;
 }
 
+// This is used by dlsym(3).  It performs symbol lookup only within the
+// specified soinfo object and its dependencies in breadth first order.
+static const ElfW(Sym)* dlsym_handle_lookup(soinfo* si,
+                                            soinfo** found,
+                                            const char* name,
+                                            const version_info* vi) {
+  // According to man dlopen(3) and posix docs in the case when si is handle
+  // of the main executable we need to search not only in the executable and its
+  // dependencies but also in all libraries loaded with RTLD_GLOBAL.
+  //
+  // Since RTLD_GLOBAL is always set for the main executable and all dt_needed shared
+  // libraries and they are loaded in breath-first (correct) order we can just execute
+  // dlsym(RTLD_DEFAULT, ...); instead of doing two stage lookup.
+  if (si == solist_get_somain()) {
+    return dlsym_linear_lookup(&g_default_namespace, name, vi, found, nullptr, RTLD_DEFAULT);
+  }
+
+  SymbolName symbol_name(name);
+  // note that the namespace is not the namespace associated with caller_addr
+  // we use ns associated with root si intentionally here. Using caller_ns
+  // causes problems when user uses dlopen_ext to open a library in the separate
+  // namespace and then calls dlsym() on the handle.
+  return dlsym_handle_lookup_impl(si->get_primary_namespace(), si, nullptr, found, symbol_name, vi);
+}
+
 soinfo* find_containing_library(const void* p) {
   // Addresses within a library may be tagged if they point to globals. Untag
   // them so that the bounds check succeeds.
diff --git a/linker/linker_namespaces.cpp b/linker/linker_namespaces.cpp
index e870ef7..b993689 100644
--- a/linker/linker_namespaces.cpp
+++ b/linker/linker_namespaces.cpp
@@ -33,6 +33,7 @@
 
 #include <dlfcn.h>
 
+// Given an absolute path, can this library be loaded into this namespace?
 bool android_namespace_t::is_accessible(const std::string& file) {
   if (!is_isolated_) {
     return true;
@@ -67,8 +68,10 @@
   return false;
 }
 
+// Are symbols from this shared object accessible for symbol lookups in a library from this
+// namespace?
 bool android_namespace_t::is_accessible(soinfo* s) {
-  auto is_accessible_ftor = [this] (soinfo* si) {
+  auto is_accessible_ftor = [this] (soinfo* si, bool allow_secondary) {
     // This is workaround for apps hacking into soinfo list.
     // and inserting their own entries into it. (http://b/37191433)
     if (!si->has_min_version(3)) {
@@ -81,20 +84,37 @@
       return true;
     }
 
-    const android_namespace_list_t& secondary_namespaces = si->get_secondary_namespaces();
-    if (secondary_namespaces.find(this) != secondary_namespaces.end()) {
-      return true;
+    // When we're looking up symbols, we want to search libraries from the same namespace (whether
+    // the namespace membership is primary or secondary), but we also want to search the immediate
+    // dependencies of libraries in our namespace. (e.g. Supposing that libapp.so -> libandroid.so
+    // crosses a namespace boundary, we want to search libandroid.so but not any of libandroid.so's
+    // dependencies).
+    //
+    // Some libraries may be present in this namespace via the secondary namespace list:
+    //  - the executable
+    //  - LD_PRELOAD and DF_1_GLOBAL libraries
+    //  - libraries inherited during dynamic namespace creation (e.g. because of
+    //    RTLD_GLOBAL / DF_1_GLOBAL / ANDROID_NAMESPACE_TYPE_SHARED)
+    //
+    // When a library's membership is secondary, we want to search its symbols, but not the symbols
+    // of its dependencies. The executable may depend on internal system libraries which should not
+    // be searched.
+    if (allow_secondary) {
+      const android_namespace_list_t& secondary_namespaces = si->get_secondary_namespaces();
+      if (secondary_namespaces.find(this) != secondary_namespaces.end()) {
+        return true;
+      }
     }
 
     return false;
   };
 
-  if (is_accessible_ftor(s)) {
+  if (is_accessible_ftor(s, true)) {
     return true;
   }
 
   return !s->get_parents().visit([&](soinfo* si) {
-    return !is_accessible_ftor(si);
+    return !is_accessible_ftor(si, false);
   });
 }
 
diff --git a/tests/Android.bp b/tests/Android.bp
index cb275a2..4bd96ad 100644
--- a/tests/Android.bp
+++ b/tests/Android.bp
@@ -747,6 +747,11 @@
         "libnstest_ns_a_public1_internal",
         "libnstest_ns_b_public2",
         "libnstest_ns_b_public3",
+        "ns_hidden_child_helper",
+        "libns_hidden_child_global",
+        "libns_hidden_child_internal",
+        "libns_hidden_child_public",
+        "libns_hidden_child_app",
         "libsegment_gap_inner",
         "libsegment_gap_outer",
         "ld_preload_test_helper",
diff --git a/tests/core_shared_libs.h b/tests/core_shared_libs.h
new file mode 100644
index 0000000..f587078
--- /dev/null
+++ b/tests/core_shared_libs.h
@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#pragma once
+
+// A new namespace should have these libraries on a link to the default namespace.
+static constexpr const char* kCoreSharedLibs = "libc.so:libc++.so:libdl.so:libm.so";
diff --git a/tests/dlext_test.cpp b/tests/dlext_test.cpp
index a2b5b3c..293c17b 100644
--- a/tests/dlext_test.cpp
+++ b/tests/dlext_test.cpp
@@ -39,6 +39,7 @@
 #include <procinfo/process_map.h>
 #include <ziparchive/zip_archive.h>
 
+#include "core_shared_libs.h"
 #include "gtest_globals.h"
 #include "utils.h"
 #include "dlext_private.h"
@@ -713,7 +714,7 @@
 static const char* g_public_lib = "libnstest_public.so";
 
 // These are libs shared with default namespace
-static const std::string g_core_shared_libs = "libc.so:libc++.so:libdl.so:libm.so";
+static const std::string g_core_shared_libs = kCoreSharedLibs;
 
 TEST(dlext, ns_smoke) {
   static const char* root_lib = "libnstest_root.so";
@@ -2055,6 +2056,23 @@
   ASSERT_TRUE(ns_get_dlopened_string_anon() != ns_get_dlopened_string_private());
 }
 
+TEST(dlext, ns_hidden_child) {
+  ExecTestHelper eth;
+
+  std::string helper = GetTestlibRoot() + "/ns_hidden_child_helper/ns_hidden_child_helper";
+  chmod(helper.c_str(), 0755); // TODO: "x" lost in CTS, b/34945607
+  std::string app_ns_dir = GetTestlibRoot() + "/ns_hidden_child_app";
+  eth.SetArgs({ helper.c_str(), app_ns_dir.c_str(), nullptr });
+
+  // Add the main libns_hidden_child_*.so libraries to the search path of the default namespace.
+  std::string env = "LD_LIBRARY_PATH=" + GetTestlibRoot();
+  eth.SetEnv({ env.c_str(), nullptr });
+
+  eth.Run([&]() { execve(helper.c_str(), eth.GetArgs(), eth.GetEnv()); }, 0,
+          "public_function is non-null\n"
+          "internal_function is null\n");
+}
+
 TEST(dlext, dlopen_handle_value_platform) {
   void* handle = dlopen("libtest_dlsym_from_this.so", RTLD_NOW | RTLD_LOCAL);
   ASSERT_TRUE((reinterpret_cast<uintptr_t>(handle) & 1) != 0)
diff --git a/tests/libs/Android.bp b/tests/libs/Android.bp
index 9be85c8..fdf2cca 100644
--- a/tests/libs/Android.bp
+++ b/tests/libs/Android.bp
@@ -469,6 +469,56 @@
 }
 
 // -----------------------------------------------------------------------------
+// ns_hidden_child linker namespace test
+// -----------------------------------------------------------------------------
+
+cc_test {
+    name: "ns_hidden_child_helper",
+    host_supported: false,
+    defaults: ["bionic_testlib_defaults"],
+    srcs: ["ns_hidden_child_helper.cpp"],
+    shared_libs: [
+        "libns_hidden_child_internal",
+        "libns_hidden_child_global",
+        "libdl_android",
+    ],
+    ldflags: ["-Wl,--rpath,${ORIGIN}/.."],
+}
+
+cc_test_library {
+    name: "libns_hidden_child_global",
+    defaults: ["bionic_testlib_defaults"],
+    host_supported: false,
+    srcs: ["ns_hidden_child_global.cpp"],
+    shared_libs: ["libns_hidden_child_internal"],
+    ldflags: ["-Wl,-z,global"],
+}
+
+cc_test_library {
+    name: "libns_hidden_child_internal",
+    defaults: ["bionic_testlib_defaults"],
+    host_supported: false,
+    srcs: ["ns_hidden_child_internal.cpp"],
+}
+
+cc_test_library {
+    name: "libns_hidden_child_public",
+    defaults: ["bionic_testlib_defaults"],
+    host_supported: false,
+    srcs: ["ns_hidden_child_public.cpp"],
+    shared_libs: ["libns_hidden_child_internal"],
+}
+
+cc_test_library {
+    name: "libns_hidden_child_app",
+    defaults: ["bionic_testlib_defaults"],
+    host_supported: false,
+    srcs: ["ns_hidden_child_app.cpp"],
+    shared_libs: ["libns_hidden_child_public"],
+    relative_install_path: "bionic-loader-test-libs/ns_hidden_child_app",
+}
+
+// -----------------------------------------------------------------------------
 // Build DT_RUNPATH test helper libraries
 //
 // Dependencies
diff --git a/tests/libs/ns_hidden_child_app.cpp b/tests/libs/ns_hidden_child_app.cpp
new file mode 100644
index 0000000..01a95cc
--- /dev/null
+++ b/tests/libs/ns_hidden_child_app.cpp
@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <stdio.h>
+
+__attribute__((weak)) extern "C" void public_function();
+__attribute__((weak)) extern "C" void internal_function();
+
+extern "C" void app_function() {
+  printf("public_function is %s\n", public_function == nullptr ? "null" : "non-null");
+  printf("internal_function is %s\n", internal_function == nullptr ? "null" : "non-null");
+}
diff --git a/tests/libs/ns_hidden_child_global.cpp b/tests/libs/ns_hidden_child_global.cpp
new file mode 100644
index 0000000..8bdcba9
--- /dev/null
+++ b/tests/libs/ns_hidden_child_global.cpp
@@ -0,0 +1,33 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+extern "C" void internal_function();
+
+extern "C" void global_function() {
+  internal_function();
+}
diff --git a/tests/libs/ns_hidden_child_helper.cpp b/tests/libs/ns_hidden_child_helper.cpp
new file mode 100644
index 0000000..c2140f1
--- /dev/null
+++ b/tests/libs/ns_hidden_child_helper.cpp
@@ -0,0 +1,85 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <android/dlext.h>
+#include <dlfcn.h>
+#include <stdlib.h>
+
+#include <string>
+
+#include "../core_shared_libs.h"
+#include "../dlext_private.h"
+
+extern "C" void global_function();
+extern "C" void internal_function();
+
+int main(int argc, char* argv[]) {
+  if (argc != 2) {
+    fprintf(stderr, "usage: %s NS_PATH\n", argv[0]);
+    fprintf(stderr, "NS_PATH   path to the ns_hidden_child_app directory\n");
+    exit(1);
+  }
+
+  // Ensure that -Wl,--needed doesn't break the test by removing DT_NEEDED entries.
+  global_function();
+  internal_function();
+
+  const char* app_lib_dir = argv[1];
+  android_namespace_t* app_ns =
+      android_create_namespace("app", nullptr, app_lib_dir, ANDROID_NAMESPACE_TYPE_ISOLATED,
+                               nullptr, nullptr);
+  if (app_ns == nullptr) {
+    fprintf(stderr, "android_create_namespace failed: %s\n", dlerror());
+    exit(1);
+  }
+
+  std::string public_libs = std::string(kCoreSharedLibs) + ":libns_hidden_child_public.so";
+  if (!android_link_namespaces(app_ns, nullptr, public_libs.c_str())) {
+    fprintf(stderr, "android_link_namespaces failed: %s\n", dlerror());
+    exit(1);
+  }
+
+  android_dlextinfo ext = {
+    .flags = ANDROID_DLEXT_USE_NAMESPACE,
+    .library_namespace = app_ns,
+  };
+  void* app_lib = android_dlopen_ext("libns_hidden_child_app.so", RTLD_NOW | RTLD_LOCAL, &ext);
+  if (app_lib == nullptr) {
+    fprintf(stderr, "android_dlopen_ext failed: %s\n", dlerror());
+    exit(1);
+  }
+
+  auto app_function = reinterpret_cast<void(*)()>(dlsym(app_lib, "app_function"));
+  if (app_function == nullptr) {
+    fprintf(stderr, "dlsym failed to find app_function: %s\n", dlerror());
+    exit(1);
+  }
+
+  app_function();
+  return 0;
+}
diff --git a/tests/libs/ns_hidden_child_internal.cpp b/tests/libs/ns_hidden_child_internal.cpp
new file mode 100644
index 0000000..23543cb
--- /dev/null
+++ b/tests/libs/ns_hidden_child_internal.cpp
@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+extern "C" void internal_function() {}
diff --git a/tests/libs/ns_hidden_child_public.cpp b/tests/libs/ns_hidden_child_public.cpp
new file mode 100644
index 0000000..1f20bd2
--- /dev/null
+++ b/tests/libs/ns_hidden_child_public.cpp
@@ -0,0 +1,33 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+extern "C" void internal_function();
+
+extern "C" void public_function() {
+  internal_function();
+}