diff --git a/libc/Android.mk b/libc/Android.mk
index 2c33a8f..4a20b3f 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -1361,6 +1361,9 @@
 # meaningful name resolution.
 LOCAL_STRIP_MODULE := keep_symbols
 
+# Do not pack libc.so relocations; see http://b/20645321 for details.
+LOCAL_PACK_MODULE_RELOCATIONS := false
+
 # WARNING: The only library libc.so should depend on is libdl.so!  If you add other libraries,
 # make sure to add -Wl,--exclude-libs=libgcc.a to the LOCAL_LDFLAGS for those libraries.  This
 # ensures that symbols that are pulled into those new libraries from libgcc.a are not declared
diff --git a/libc/bionic/system_properties.cpp b/libc/bionic/system_properties.cpp
index aae99b1..c436a16 100644
--- a/libc/bionic/system_properties.cpp
+++ b/libc/bionic/system_properties.cpp
@@ -598,6 +598,16 @@
     return map_prop_area_rw();
 }
 
+unsigned int __system_property_area_serial()
+{
+    prop_area *pa = __system_property_area__;
+    if (!pa) {
+        return -1;
+    }
+    // Make sure this read fulfilled before __system_property_serial
+    return atomic_load_explicit(&(pa->serial), memory_order_acquire);
+}
+
 const prop_info *__system_property_find(const char *name)
 {
     if (__predict_false(compat_mode)) {
diff --git a/libc/include/sys/_system_properties.h b/libc/include/sys/_system_properties.h
index 7ff3ded..c200295 100644
--- a/libc/include/sys/_system_properties.h
+++ b/libc/include/sys/_system_properties.h
@@ -98,6 +98,24 @@
 */
 int __system_property_area_init();
 
+/* Read the global serial number of the system properties
+**
+** Called to predict if a series of cached __system_property_find
+** objects will have seen __system_property_serial values change.
+** But also aids the converse, as changes in the global serial can
+** also be used to predict if a failed __system_property_find
+** could in-turn now find an new object; thus preventing the
+** cycles of effort to poll __system_property_find.
+**
+** Called at the beginning of a cache cycle to signal _any_ possible
+** changes have occurred since last. If there is, check each individual
+** __system_property_serial to confirm dirty, or __system_property_find
+** to check if the property now exists.
+**
+** Returns the serial number on success, -1 on error.
+*/
+unsigned int __system_property_area_serial();
+
 /* Add a new system property.  Can only be done by a single
 ** process that has write access to the property area, and
 ** that process must handle sequencing to ensure the property
diff --git a/linker/linker_environ.cpp b/linker/linker_environ.cpp
index 9a0f009..3c466a2 100644
--- a/linker/linker_environ.cpp
+++ b/linker/linker_environ.cpp
@@ -36,7 +36,6 @@
 
 #include "private/KernelArgumentBlock.h"
 
-static char** _envp;
 static bool _AT_SECURE_value = true;
 
 bool get_AT_SECURE() {
@@ -150,8 +149,8 @@
 }
 
 static void __sanitize_environment_variables() {
-  char** src  = _envp;
-  char** dst = _envp;
+  char** src  = environ;
+  char** dst = environ;
   for (; src[0] != nullptr; ++src) {
     if (!__is_valid_environment_variable(src[0])) {
       continue;
@@ -168,7 +167,7 @@
 
 void linker_env_init(KernelArgumentBlock& args) {
   // Store environment pointer - can't be null.
-  _envp = args.envp;
+  environ = args.envp;
 
   __init_AT_SECURE(args);
   __sanitize_environment_variables();
@@ -179,7 +178,7 @@
     return nullptr;
   }
 
-  for (char** p = _envp; p[0] != nullptr; ++p) {
+  for (char** p = environ; p[0] != nullptr; ++p) {
     const char* val = env_match(p[0], name);
     if (val != nullptr) {
       if (val[0] == '\0') {