diff --git a/libc/Android.bp b/libc/Android.bp
index 53db888..b7cb59d 100644
--- a/libc/Android.bp
+++ b/libc/Android.bp
@@ -927,22 +927,41 @@
                 "arch-x86/generic/string/wcscpy.c",
                 "arch-x86/generic/string/wmemcmp.c",
 
-                "arch-x86/atom/string/sse2-memchr-atom.S",
-                "arch-x86/atom/string/sse2-memrchr-atom.S",
-                "arch-x86/atom/string/sse2-strchr-atom.S",
-                "arch-x86/atom/string/sse2-strnlen-atom.S",
-                "arch-x86/atom/string/sse2-strrchr-atom.S",
-                "arch-x86/atom/string/sse2-wcschr-atom.S",
-                "arch-x86/atom/string/sse2-wcsrchr-atom.S",
-                "arch-x86/atom/string/sse2-wcslen-atom.S",
-                "arch-x86/atom/string/sse2-wcscmp-atom.S",
-                "arch-x86/silvermont/string/sse2-memmove-slm.S",
-                "arch-x86/silvermont/string/sse2-memset-slm.S",
-                "arch-x86/silvermont/string/sse2-stpcpy-slm.S",
-                "arch-x86/silvermont/string/sse2-stpncpy-slm.S",
-                "arch-x86/silvermont/string/sse2-strcpy-slm.S",
-                "arch-x86/silvermont/string/sse2-strlen-slm.S",
-                "arch-x86/silvermont/string/sse2-strncpy-slm.S",
+                "arch-x86/string/sse2-memchr-atom.S",
+                "arch-x86/string/sse2-memmove-slm.S",
+                "arch-x86/string/sse2-memrchr-atom.S",
+                "arch-x86/string/sse2-memset-atom.S",
+                "arch-x86/string/sse2-memset-slm.S",
+                "arch-x86/string/sse2-stpcpy-slm.S",
+                "arch-x86/string/sse2-stpncpy-slm.S",
+                "arch-x86/string/sse2-strchr-atom.S",
+                "arch-x86/string/sse2-strcpy-slm.S",
+                "arch-x86/string/sse2-strlen-slm.S",
+                "arch-x86/string/sse2-strncpy-slm.S",
+                "arch-x86/string/sse2-strnlen-atom.S",
+                "arch-x86/string/sse2-strrchr-atom.S",
+                "arch-x86/string/sse2-wcschr-atom.S",
+                "arch-x86/string/sse2-wcsrchr-atom.S",
+                "arch-x86/string/sse2-wcslen-atom.S",
+                "arch-x86/string/sse2-wcscmp-atom.S",
+                "arch-x86/string/sse2-strlen-atom.S",
+
+                "arch-x86/string/ssse3-memcmp-atom.S",
+                "arch-x86/string/ssse3-memmove-atom.S",
+                "arch-x86/string/ssse3-strcat-atom.S",
+                "arch-x86/string/ssse3-strcmp-atom.S",
+                "arch-x86/string/ssse3-strcpy-atom.S",
+                "arch-x86/string/ssse3-strlcat-atom.S",
+                "arch-x86/string/ssse3-strlcpy-atom.S",
+                "arch-x86/string/ssse3-strncat-atom.S",
+                "arch-x86/string/ssse3-strncmp-atom.S",
+                "arch-x86/string/ssse3-strncpy-atom.S",
+                "arch-x86/string/ssse3-wcscat-atom.S",
+                "arch-x86/string/ssse3-wcscpy-atom.S",
+                "arch-x86/string/ssse3-wmemcmp-atom.S",
+
+                "arch-x86/string/sse4-memcmp-slm.S",
+                "arch-x86/string/sse4-wmemcmp-slm.S",
 
                 "arch-x86/bionic/__bionic_clone.S",
                 "arch-x86/bionic/_exit_with_stack_teardown.S",
@@ -952,29 +971,6 @@
                 "arch-x86/bionic/syscall.S",
                 "arch-x86/bionic/vfork.S",
                 "arch-x86/bionic/__x86.get_pc_thunk.S",
-
-                // ssse3 functions
-                "arch-x86/atom/string/ssse3-strcat-atom.S",
-                "arch-x86/atom/string/ssse3-strcmp-atom.S",
-                "arch-x86/atom/string/ssse3-strlcat-atom.S",
-                "arch-x86/atom/string/ssse3-strlcpy-atom.S",
-                "arch-x86/atom/string/ssse3-strncat-atom.S",
-                "arch-x86/atom/string/ssse3-strncmp-atom.S",
-                "arch-x86/atom/string/ssse3-wcscat-atom.S",
-                "arch-x86/atom/string/ssse3-wcscpy-atom.S",
-
-                // sse4 functions
-                "arch-x86/silvermont/string/sse4-memcmp-slm.S",
-                "arch-x86/silvermont/string/sse4-wmemcmp-slm.S",
-
-                // atom functions
-                "arch-x86/atom/string/sse2-memset-atom.S",
-                "arch-x86/atom/string/sse2-strlen-atom.S",
-                "arch-x86/atom/string/ssse3-memcmp-atom.S",
-                "arch-x86/atom/string/ssse3-memmove-atom.S",
-                "arch-x86/atom/string/ssse3-strcpy-atom.S",
-                "arch-x86/atom/string/ssse3-strncpy-atom.S",
-                "arch-x86/atom/string/ssse3-wmemcmp-atom.S",
             ],
 
             exclude_srcs: [
diff --git a/libc/arch-x86/atom/string/cache.h b/libc/arch-x86/atom/string/cache.h
deleted file mode 100644
index 823bb1e..0000000
--- a/libc/arch-x86/atom/string/cache.h
+++ /dev/null
@@ -1,36 +0,0 @@
-/*
-Copyright (c) 2010, Intel Corporation
-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.
-
-    * Neither the name of Intel Corporation nor the names of its contributors
-    * may be used to endorse or promote products derived from this software
-    * without specific prior written permission.
-
-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.
-*/
-
-/* Values are optimized for Atom */
-#define SHARED_CACHE_SIZE	(512*1024)			/* Atom L2 Cache */
-#define DATA_CACHE_SIZE		(24*1024)			/* Atom L1 Data Cache */
-
-#define SHARED_CACHE_SIZE_HALF	(SHARED_CACHE_SIZE / 2)
-#define DATA_CACHE_SIZE_HALF	(DATA_CACHE_SIZE / 2)
diff --git a/libc/arch-x86/silvermont/string/cache.h b/libc/arch-x86/string/cache.h
similarity index 80%
rename from libc/arch-x86/silvermont/string/cache.h
rename to libc/arch-x86/string/cache.h
index c342b1c..33719a0 100644
--- a/libc/arch-x86/silvermont/string/cache.h
+++ b/libc/arch-x86/string/cache.h
@@ -28,9 +28,14 @@
 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
-/* Values are optimized for Silvermont */
-#define SHARED_CACHE_SIZE	(1024*1024)			/* Silvermont L2 Cache */
-#define DATA_CACHE_SIZE		(24*1024)			/* Silvermont L1 Data Cache */
+#ifdef FOR_ATOM
+#define SHARED_CACHE_SIZE (512 * 1024) /* Atom L2 Cache */
+#endif
+#ifdef FOR_SILVERMONT
+#define SHARED_CACHE_SIZE (1024 * 1024) /* Silvermont L2 Cache */
+#endif
 
-#define SHARED_CACHE_SIZE_HALF	(SHARED_CACHE_SIZE / 2)
-#define DATA_CACHE_SIZE_HALF	(DATA_CACHE_SIZE / 2)
+#define DATA_CACHE_SIZE (24 * 1024) /* Atom and Silvermont L1 Data Cache */
+
+#define SHARED_CACHE_SIZE_HALF (SHARED_CACHE_SIZE / 2)
+#define DATA_CACHE_SIZE_HALF (DATA_CACHE_SIZE / 2)
diff --git a/libc/arch-x86/atom/string/sse2-memchr-atom.S b/libc/arch-x86/string/sse2-memchr-atom.S
similarity index 100%
rename from libc/arch-x86/atom/string/sse2-memchr-atom.S
rename to libc/arch-x86/string/sse2-memchr-atom.S
diff --git a/libc/arch-x86/silvermont/string/sse2-memmove-slm.S b/libc/arch-x86/string/sse2-memmove-slm.S
similarity index 99%
rename from libc/arch-x86/silvermont/string/sse2-memmove-slm.S
rename to libc/arch-x86/string/sse2-memmove-slm.S
index da6456c..79b5d1b 100644
--- a/libc/arch-x86/silvermont/string/sse2-memmove-slm.S
+++ b/libc/arch-x86/string/sse2-memmove-slm.S
@@ -28,6 +28,7 @@
 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
+#define FOR_SILVERMONT
 #include "cache.h"
 
 #ifndef MEMMOVE
diff --git a/libc/arch-x86/atom/string/sse2-memrchr-atom.S b/libc/arch-x86/string/sse2-memrchr-atom.S
similarity index 100%
rename from libc/arch-x86/atom/string/sse2-memrchr-atom.S
rename to libc/arch-x86/string/sse2-memrchr-atom.S
diff --git a/libc/arch-x86/atom/string/sse2-memset-atom.S b/libc/arch-x86/string/sse2-memset-atom.S
similarity index 99%
rename from libc/arch-x86/atom/string/sse2-memset-atom.S
rename to libc/arch-x86/string/sse2-memset-atom.S
index e4cd038..320afec 100644
--- a/libc/arch-x86/atom/string/sse2-memset-atom.S
+++ b/libc/arch-x86/string/sse2-memset-atom.S
@@ -30,6 +30,7 @@
 
 #include <private/bionic_asm.h>
 
+#define FOR_ATOM
 #include "cache.h"
 
 #ifndef L
diff --git a/libc/arch-x86/silvermont/string/sse2-memset-slm.S b/libc/arch-x86/string/sse2-memset-slm.S
similarity index 99%
rename from libc/arch-x86/silvermont/string/sse2-memset-slm.S
rename to libc/arch-x86/string/sse2-memset-slm.S
index b7633f5..5cff141 100644
--- a/libc/arch-x86/silvermont/string/sse2-memset-slm.S
+++ b/libc/arch-x86/string/sse2-memset-slm.S
@@ -30,6 +30,7 @@
 
 #include <private/bionic_asm.h>
 
+#define FOR_SILVERMONT
 #include "cache.h"
 
 #ifndef L
diff --git a/libc/arch-x86/silvermont/string/sse2-stpcpy-slm.S b/libc/arch-x86/string/sse2-stpcpy-slm.S
similarity index 100%
rename from libc/arch-x86/silvermont/string/sse2-stpcpy-slm.S
rename to libc/arch-x86/string/sse2-stpcpy-slm.S
diff --git a/libc/arch-x86/silvermont/string/sse2-stpncpy-slm.S b/libc/arch-x86/string/sse2-stpncpy-slm.S
similarity index 100%
rename from libc/arch-x86/silvermont/string/sse2-stpncpy-slm.S
rename to libc/arch-x86/string/sse2-stpncpy-slm.S
diff --git a/libc/arch-x86/atom/string/sse2-strchr-atom.S b/libc/arch-x86/string/sse2-strchr-atom.S
similarity index 100%
rename from libc/arch-x86/atom/string/sse2-strchr-atom.S
rename to libc/arch-x86/string/sse2-strchr-atom.S
diff --git a/libc/arch-x86/silvermont/string/sse2-strcpy-slm.S b/libc/arch-x86/string/sse2-strcpy-slm.S
similarity index 100%
rename from libc/arch-x86/silvermont/string/sse2-strcpy-slm.S
rename to libc/arch-x86/string/sse2-strcpy-slm.S
diff --git a/libc/arch-x86/atom/string/sse2-strlen-atom.S b/libc/arch-x86/string/sse2-strlen-atom.S
similarity index 100%
rename from libc/arch-x86/atom/string/sse2-strlen-atom.S
rename to libc/arch-x86/string/sse2-strlen-atom.S
diff --git a/libc/arch-x86/silvermont/string/sse2-strlen-slm.S b/libc/arch-x86/string/sse2-strlen-slm.S
similarity index 100%
rename from libc/arch-x86/silvermont/string/sse2-strlen-slm.S
rename to libc/arch-x86/string/sse2-strlen-slm.S
diff --git a/libc/arch-x86/silvermont/string/sse2-strncpy-slm.S b/libc/arch-x86/string/sse2-strncpy-slm.S
similarity index 100%
rename from libc/arch-x86/silvermont/string/sse2-strncpy-slm.S
rename to libc/arch-x86/string/sse2-strncpy-slm.S
diff --git a/libc/arch-x86/atom/string/sse2-strnlen-atom.S b/libc/arch-x86/string/sse2-strnlen-atom.S
similarity index 100%
rename from libc/arch-x86/atom/string/sse2-strnlen-atom.S
rename to libc/arch-x86/string/sse2-strnlen-atom.S
diff --git a/libc/arch-x86/atom/string/sse2-strrchr-atom.S b/libc/arch-x86/string/sse2-strrchr-atom.S
similarity index 100%
rename from libc/arch-x86/atom/string/sse2-strrchr-atom.S
rename to libc/arch-x86/string/sse2-strrchr-atom.S
diff --git a/libc/arch-x86/atom/string/sse2-wcschr-atom.S b/libc/arch-x86/string/sse2-wcschr-atom.S
similarity index 100%
rename from libc/arch-x86/atom/string/sse2-wcschr-atom.S
rename to libc/arch-x86/string/sse2-wcschr-atom.S
diff --git a/libc/arch-x86/atom/string/sse2-wcscmp-atom.S b/libc/arch-x86/string/sse2-wcscmp-atom.S
similarity index 100%
rename from libc/arch-x86/atom/string/sse2-wcscmp-atom.S
rename to libc/arch-x86/string/sse2-wcscmp-atom.S
diff --git a/libc/arch-x86/atom/string/sse2-wcslen-atom.S b/libc/arch-x86/string/sse2-wcslen-atom.S
similarity index 100%
rename from libc/arch-x86/atom/string/sse2-wcslen-atom.S
rename to libc/arch-x86/string/sse2-wcslen-atom.S
diff --git a/libc/arch-x86/atom/string/sse2-wcsrchr-atom.S b/libc/arch-x86/string/sse2-wcsrchr-atom.S
similarity index 100%
rename from libc/arch-x86/atom/string/sse2-wcsrchr-atom.S
rename to libc/arch-x86/string/sse2-wcsrchr-atom.S
diff --git a/libc/arch-x86/silvermont/string/sse4-memcmp-slm.S b/libc/arch-x86/string/sse4-memcmp-slm.S
similarity index 100%
rename from libc/arch-x86/silvermont/string/sse4-memcmp-slm.S
rename to libc/arch-x86/string/sse4-memcmp-slm.S
diff --git a/libc/arch-x86/silvermont/string/sse4-wmemcmp-slm.S b/libc/arch-x86/string/sse4-wmemcmp-slm.S
similarity index 100%
rename from libc/arch-x86/silvermont/string/sse4-wmemcmp-slm.S
rename to libc/arch-x86/string/sse4-wmemcmp-slm.S
diff --git a/libc/arch-x86/atom/string/ssse3-memcmp-atom.S b/libc/arch-x86/string/ssse3-memcmp-atom.S
similarity index 100%
rename from libc/arch-x86/atom/string/ssse3-memcmp-atom.S
rename to libc/arch-x86/string/ssse3-memcmp-atom.S
diff --git a/libc/arch-x86/atom/string/ssse3-memcpy-atom.S b/libc/arch-x86/string/ssse3-memcpy-atom.S
similarity index 99%
rename from libc/arch-x86/atom/string/ssse3-memcpy-atom.S
rename to libc/arch-x86/string/ssse3-memcpy-atom.S
index 5532e2e..fe3082e 100644
--- a/libc/arch-x86/atom/string/ssse3-memcpy-atom.S
+++ b/libc/arch-x86/string/ssse3-memcpy-atom.S
@@ -28,6 +28,7 @@
 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
+#define FOR_ATOM
 #include "cache.h"
 
 #ifndef MEMCPY
diff --git a/libc/arch-x86/atom/string/ssse3-memmove-atom.S b/libc/arch-x86/string/ssse3-memmove-atom.S
similarity index 100%
rename from libc/arch-x86/atom/string/ssse3-memmove-atom.S
rename to libc/arch-x86/string/ssse3-memmove-atom.S
diff --git a/libc/arch-x86/atom/string/ssse3-strcat-atom.S b/libc/arch-x86/string/ssse3-strcat-atom.S
similarity index 100%
rename from libc/arch-x86/atom/string/ssse3-strcat-atom.S
rename to libc/arch-x86/string/ssse3-strcat-atom.S
diff --git a/libc/arch-x86/atom/string/ssse3-strcmp-atom.S b/libc/arch-x86/string/ssse3-strcmp-atom.S
similarity index 100%
rename from libc/arch-x86/atom/string/ssse3-strcmp-atom.S
rename to libc/arch-x86/string/ssse3-strcmp-atom.S
diff --git a/libc/arch-x86/atom/string/ssse3-strcpy-atom.S b/libc/arch-x86/string/ssse3-strcpy-atom.S
similarity index 100%
rename from libc/arch-x86/atom/string/ssse3-strcpy-atom.S
rename to libc/arch-x86/string/ssse3-strcpy-atom.S
diff --git a/libc/arch-x86/atom/string/ssse3-strlcat-atom.S b/libc/arch-x86/string/ssse3-strlcat-atom.S
similarity index 100%
rename from libc/arch-x86/atom/string/ssse3-strlcat-atom.S
rename to libc/arch-x86/string/ssse3-strlcat-atom.S
diff --git a/libc/arch-x86/atom/string/ssse3-strlcpy-atom.S b/libc/arch-x86/string/ssse3-strlcpy-atom.S
similarity index 100%
rename from libc/arch-x86/atom/string/ssse3-strlcpy-atom.S
rename to libc/arch-x86/string/ssse3-strlcpy-atom.S
diff --git a/libc/arch-x86/atom/string/ssse3-strncat-atom.S b/libc/arch-x86/string/ssse3-strncat-atom.S
similarity index 100%
rename from libc/arch-x86/atom/string/ssse3-strncat-atom.S
rename to libc/arch-x86/string/ssse3-strncat-atom.S
diff --git a/libc/arch-x86/atom/string/ssse3-strncmp-atom.S b/libc/arch-x86/string/ssse3-strncmp-atom.S
similarity index 100%
rename from libc/arch-x86/atom/string/ssse3-strncmp-atom.S
rename to libc/arch-x86/string/ssse3-strncmp-atom.S
diff --git a/libc/arch-x86/atom/string/ssse3-strncpy-atom.S b/libc/arch-x86/string/ssse3-strncpy-atom.S
similarity index 100%
rename from libc/arch-x86/atom/string/ssse3-strncpy-atom.S
rename to libc/arch-x86/string/ssse3-strncpy-atom.S
diff --git a/libc/arch-x86/atom/string/ssse3-wcscat-atom.S b/libc/arch-x86/string/ssse3-wcscat-atom.S
similarity index 100%
rename from libc/arch-x86/atom/string/ssse3-wcscat-atom.S
rename to libc/arch-x86/string/ssse3-wcscat-atom.S
diff --git a/libc/arch-x86/atom/string/ssse3-wcscpy-atom.S b/libc/arch-x86/string/ssse3-wcscpy-atom.S
similarity index 100%
rename from libc/arch-x86/atom/string/ssse3-wcscpy-atom.S
rename to libc/arch-x86/string/ssse3-wcscpy-atom.S
diff --git a/libc/arch-x86/atom/string/ssse3-wmemcmp-atom.S b/libc/arch-x86/string/ssse3-wmemcmp-atom.S
similarity index 100%
rename from libc/arch-x86/atom/string/ssse3-wmemcmp-atom.S
rename to libc/arch-x86/string/ssse3-wmemcmp-atom.S
diff --git a/libc/tzcode/strftime.c b/libc/tzcode/strftime.c
index 8c1b983..d04c5ba 100644
--- a/libc/tzcode/strftime.c
+++ b/libc/tzcode/strftime.c
@@ -190,6 +190,29 @@
     return normal;
 }
 
+// Android-added: fall back mechanism when TM_ZONE is not initialized.
+#ifdef TM_ZONE
+static const char* _safe_tm_zone(const struct tm* tm) {
+  const char* zone = tm->TM_ZONE;
+  if (!zone || !*zone) {
+    // "The value of tm_isdst shall be positive if Daylight Savings Time is
+    // in effect, 0 if Daylight Savings Time is not in effect, and negative
+    // if the information is not available."
+    if (tm->tm_isdst == 0) {
+      zone = tzname[0];
+    } else if (tm->tm_isdst > 0) {
+      zone = tzname[1];
+    }
+
+    // "Replaced by the timezone name or abbreviation, or by no bytes if no
+    // timezone information exists."
+    if (!zone || !*zone) zone = "";
+  }
+
+  return zone;
+}
+#endif
+
 static char *
 _fmt(const char *format, const struct tm *t, char *pt,
         const char *ptlim, enum warn *warnp)
@@ -524,21 +547,7 @@
             case 'Z':
 #ifdef TM_ZONE
                 // BEGIN: Android-changed.
-                {
-                    const char* zone = t->TM_ZONE;
-                    if (!zone || !*zone) {
-                        // "The value of tm_isdst shall be positive if Daylight Savings Time is
-                        // in effect, 0 if Daylight Savings Time is not in effect, and negative
-                        // if the information is not available."
-                        if (t->tm_isdst == 0) zone = tzname[0];
-                        else if (t->tm_isdst > 0) zone = tzname[1];
-
-                        // "Replaced by the timezone name or abbreviation, or by no bytes if no
-                        // timezone information exists."
-                        if (!zone || !*zone) zone = "";
-                    }
-                    pt = _add(zone, pt, ptlim, modifier);
-                }
+                pt = _add(_safe_tm_zone(t), pt, ptlim, modifier);
                 // END: Android-changed.
 #elif HAVE_TZNAME
                 if (t->tm_isdst >= 0)
@@ -599,7 +608,11 @@
                 negative = diff < 0;
                 if (diff == 0) {
 #ifdef TM_ZONE
-                    negative = t->TM_ZONE[0] == '-';
+                  // Android-changed: do not use TM_ZONE as it is as it may be null.
+                  {
+                    const char* zone = _safe_tm_zone(t);
+                    negative = zone[0] == '-';
+                  }
 #else
                     negative = t->tm_isdst < 0;
 # if HAVE_TZNAME
diff --git a/tests/time_test.cpp b/tests/time_test.cpp
index 898496d..40e5c6d 100644
--- a/tests/time_test.cpp
+++ b/tests/time_test.cpp
@@ -266,7 +266,7 @@
   EXPECT_STREQ("-1", buf);
 }
 
-TEST(time, strftime_null_tm_zone) {
+TEST(time, strftime_Z_null_tm_zone) {
   // Netflix on Nexus Player wouldn't start (http://b/25170306).
   struct tm t;
   memset(&t, 0, sizeof(tm));
@@ -304,6 +304,86 @@
 #endif
 }
 
+// According to C language specification the only tm struct field needed to
+// find out replacement for %z and %Z in strftime is tm_isdst. Which is
+// wrong, as time zones change their standard offset and even DST savings.
+// tzcode deviates from C language specification and requires tm struct either
+// to be output of localtime-like functions or to be modified by mktime call
+// before passing to strftime. See tz mailing discussion for more details
+// https://mm.icann.org/pipermail/tz/2022-July/031674.html
+// But we are testing case when tm.tm_zone is null, which means that tm struct
+// is not coming from localtime and is neither modified by mktime. That's why
+// we are comparing against +0000, even though America/Los_Angeles never
+// observes it.
+TEST(time, strftime_z_null_tm_zone) {
+  char str[64];
+  struct tm tm = {.tm_year = 109, .tm_mon = 4, .tm_mday = 2, .tm_isdst = 0};
+
+  setenv("TZ", "America/Los_Angeles", 1);
+  tzset();
+
+  tm.tm_zone = NULL;
+
+  size_t result = strftime(str, sizeof(str), "%z", &tm);
+
+  EXPECT_EQ(5U, result);
+  EXPECT_STREQ("+0000", str);
+
+  tm.tm_isdst = 1;
+
+  result = strftime(str, sizeof(str), "%z", &tm);
+
+  EXPECT_EQ(5U, result);
+  EXPECT_STREQ("+0000", str);
+
+  setenv("TZ", "UTC", 1);
+  tzset();
+
+  tm.tm_isdst = 0;
+
+  result = strftime(str, sizeof(str), "%z", &tm);
+
+  EXPECT_EQ(5U, result);
+  EXPECT_STREQ("+0000", str);
+
+  tm.tm_isdst = 1;
+
+  result = strftime(str, sizeof(str), "%z", &tm);
+
+  EXPECT_EQ(5U, result);
+  EXPECT_STREQ("+0000", str);
+}
+
+TEST(time, strftime_z_Europe_Lisbon) {
+  char str[64];
+  // During 1992-1996 Europe/Lisbon standard offset was 1 hour.
+  // tm_isdst is not set as it will be overridden by mktime call anyway.
+  struct tm tm = {.tm_year = 1996 - 1900, .tm_mon = 2, .tm_mday = 13};
+
+  setenv("TZ", "Europe/Lisbon", 1);
+  tzset();
+
+  // tzcode's strftime implementation for %z relies on prior mktime call.
+  // At the moment of writing %z value is taken from tm_gmtoff. So without
+  // mktime call %z is replaced with +0000.
+  // See https://mm.icann.org/pipermail/tz/2022-July/031674.html
+  mktime(&tm);
+
+  size_t result = strftime(str, sizeof(str), "%z", &tm);
+
+  EXPECT_EQ(5U, result);
+  EXPECT_STREQ("+0100", str);
+
+  // Now standard offset is 0.
+  tm = {.tm_year = 2022 - 1900, .tm_mon = 2, .tm_mday = 13};
+
+  mktime(&tm);
+  result = strftime(str, sizeof(str), "%z", &tm);
+
+  EXPECT_EQ(5U, result);
+  EXPECT_STREQ("+0000", str);
+}
+
 TEST(time, strftime_l) {
   locale_t cloc = newlocale(LC_ALL, "C.UTF-8", nullptr);
   locale_t old_locale = uselocale(cloc);