diff --git a/glibc-upstream-amx-detection.patch b/glibc-upstream-amx-detection.patch
new file mode 100644
index 0000000..c2869d2
--- /dev/null
+++ b/glibc-upstream-amx-detection.patch
@@ -0,0 +1,26 @@
+commit 7fc9152e831fb24091c0ceabdcecb9b07dd29dd6
+Author: H.J. Lu <hjl.tools@gmail.com>
+Date:   Wed Apr 21 18:40:08 2021 -0700
+
+    x86: tst-cpu-features-supports.c: Update AMX check
+    
+    Pass "amx-bf16", "amx-int8" and "amx-tile", instead of "amx_bf16",
+    "amx_int8" and "amx_tile", to __builtin_cpu_supports for GCC 11.
+
+diff --git a/sysdeps/x86/tst-cpu-features-supports.c b/sysdeps/x86/tst-cpu-features-supports.c
+index ce78a7d8bcce75a4..a2cabc90beeb9530 100644
+--- a/sysdeps/x86/tst-cpu-features-supports.c
++++ b/sysdeps/x86/tst-cpu-features-supports.c
+@@ -59,9 +59,9 @@ do_test (int argc, char **argv)
+   fails += CHECK_SUPPORTS (aes, AES);
+ #endif
+ #if __GNUC_PREREQ (11, 1)
+-  fails += CHECK_SUPPORTS (amx_bf16, AMX_BF16);
+-  fails += CHECK_SUPPORTS (amx_int8, AMX_INT8);
+-  fails += CHECK_SUPPORTS (amx_tile, AMX_TILE);
++  fails += CHECK_SUPPORTS (amx-bf16, AMX_BF16);
++  fails += CHECK_SUPPORTS (amx-int8, AMX_INT8);
++  fails += CHECK_SUPPORTS (amx-tile, AMX_TILE);
+ #endif
+   fails += CHECK_SUPPORTS (avx, AVX);
+   fails += CHECK_SUPPORTS (avx2, AVX2);
diff --git a/glibc-upstream-malloc-test-hang.patch b/glibc-upstream-malloc-test-hang.patch
new file mode 100644
index 0000000..db691ac
--- /dev/null
+++ b/glibc-upstream-malloc-test-hang.patch
@@ -0,0 +1,31 @@
+commit 0a282de11b87fb4ad015c0cd10158555999705f9
+Author: Arjun Shankar <arjun@redhat.com>
+Date:   Wed Apr 7 00:30:11 2021 +0200
+
+    malloc: Run tst-malloc-stats-cancellation via test-driver.c
+    
+    This allows the test to time out in case it hangs.
+    
+    Reviewed-by: Carlos O'Donell <carlos@redhat.com>
+
+diff --git a/malloc/tst-malloc-stats-cancellation.c b/malloc/tst-malloc-stats-cancellation.c
+index 9a8f475830b16af2..725cad6498f3cdf8 100644
+--- a/malloc/tst-malloc-stats-cancellation.c
++++ b/malloc/tst-malloc-stats-cancellation.c
+@@ -91,8 +91,8 @@ buffer_threadproc (void *argp)
+ }
+ 
+ 
+-int
+-main (void)
++static int
++do_test (void)
+ {
+   int result = 0, err, real_stderr_fd, bufpipe[2];
+   pthread_t t_thr, b_thr;
+@@ -214,3 +214,5 @@ main (void)
+     }
+   return result;
+ }
++
++#include <support/test-driver.c>
diff --git a/glibc.spec b/glibc.spec
index 0ece4ac..ab3139a 100644
--- a/glibc.spec
+++ b/glibc.spec
@@ -27,8 +27,8 @@
 %bcond_without benchtests
 # Default: Not bootstrapping.
 %bcond_with bootstrap
-# Default: Disable -Werror due to GCC PR98512.
-%bcond_with werror
+# Default: Enable using -Werror
+%bcond_without werror
 # Default: Always build documentation.
 %bcond_without docs
 
@@ -65,6 +65,14 @@
 %define buildpower9 0
 %endif
 
+# The annobin annotations cause binutils to produce broken ARM EABI
+# unwinding information.  Symptom is a hang/test failure for
+# malloc/tst-malloc-stats-cancellation.  See
+# <https://bugzilla.redhat.com/show_bug.cgi?id=1951492>.
+%ifarch armv7hl
+%undefine _annotated_build
+%endif
+
 ##############################################################################
 # Any architecture/kernel combination that supports running 32-bit and 64-bit
 # code in userspace is considered a biarch arch.
@@ -96,7 +104,7 @@
 Summary: The GNU libc libraries
 Name: glibc
 Version: %{glibcversion}
-Release: 3%{?dist}
+Release: 4%{?dist}
 
 # In general, GPLv2+ is used by programs, LGPLv2+ is used for
 # libraries.
@@ -154,6 +162,8 @@ Patch23: glibc-python3.patch
 Patch29: glibc-fedora-nsswitch.patch
 Patch30: glibc-deprecated-selinux-makedb.patch
 Patch31: glibc-deprecated-selinux-nscd.patch
+Patch32: glibc-upstream-amx-detection.patch
+Patch33: glibc-upstream-malloc-test-hang.patch
 
 ##############################################################################
 # Continued list of core "glibc" package information:
@@ -2300,6 +2310,18 @@ fi
 %files -f compat-libpthread-nonshared.filelist -n compat-libpthread-nonshared
 
 %changelog
+* Tue May  4 2021 Florian Weimer <fweimer@redhat.com> - 2.33.9000-4
+- Various changes to get glibc building again, using selected upstream
+  backports.
+- Re-enable -Werror by default.
+- This release introduces __libc_start_main@@GLIBC_2.34, so binaries
+  are not compatible with glibc 2.33.  Building binaries against this
+  glibc version is not recommended because of the partial libpthread
+  transition.
+- glibc-upstream-amx-detection.patch: Fix build failure after GCC 11.1 update.
+- glibc-upstream-malloc-test-hang.patch: Avoid test hang due to
+  annobin/binutils bug (#1951492)
+
 * Wed Mar 03 2021 Arjun Shankar <arjun@redhat.com> - 2.33.9000-3
 - Drop glibc-rh819430.patch; fixed upstream.
 - Auto-sync with upstream branch master,