diff --git a/testing/firefox/build b/testing/firefox/build
index abd96dfc..772894c3 100755
--- a/testing/firefox/build
+++ b/testing/firefox/build
@@ -18,13 +18,18 @@ export LDFLAGS="$LDFLAGS -Wl,-rpath=/usr/lib/firefox"
 export CC=${CC:-gcc}
 export CXX=${CXX:-g++}
 
+# Keep memory usage as low as possible.
+export LDFLAGS="$LDFLAGS -Wl,--as-needed -Wl,--no-keep-memory -Wl,--stats"
+export MOZ_LINK_FLAGS=$LDFLAGS
+export MOZ_DEBUG_FLAGS=-g0
+export RUSTFLAGS=-Cdebuginfo=0
+
 for patch in *.patch; do
     patch -p1 < "$patch"
 done
 
-# Fix OOM errors.
-cores=$(nproc)
-printf '%s\n' "mk_add_options MOZ_MAKE_FLAGS=\"-j$cores -l$cores\"" >> mozconfig
+printf 'mk_add_options MOZ_MAKE_FLAGS="%s"\n' \
+    "${MAKEFLAGS:--j1 -l1}" >> mozconfig
 
 ./mach build
 DESTDIR="$1" ./mach install
diff --git a/testing/firefox/checksums b/testing/firefox/checksums
index 3fc2b9df..340d479f 100644
--- a/testing/firefox/checksums
+++ b/testing/firefox/checksums
@@ -7,4 +7,5 @@ b5e70b12cc9dd18fffd7924a7d3a2e11574136fe0764359d08eba0755f1c5d4c  mozconfig
 b19aaae7fc45db643f8d2540d96919c745ea341e36d9aea2df40e3e90eb951f0  fix-toolkit.patch
 e24f71a6a0d8d4637b2081780c66b01be4eeb4dd496031270d0ae0b898be94d2  fix-tools.patch
 5e0fcfde375837074baad21a8ab26aa442a7940617ebd074a6b238a48f2ceb63  fix-webrtc-glibcisms.patch
+800965f5071d6f84ca99382f1ffd41b0683e3e9e704acbd415923a8b2d209761  fix-bug-1261392.patch
 1d4a8f110d34da478f5597727eda9acacebd443dd86cce5bb64f898c01feabce  mallinfo.patch
diff --git a/testing/firefox/patches/fix-bug-1261392.patch b/testing/firefox/patches/fix-bug-1261392.patch
new file mode 100644
index 00000000..fa40914d
--- /dev/null
+++ b/testing/firefox/patches/fix-bug-1261392.patch
@@ -0,0 +1,25 @@
+--- a/tools/profiler/core/platform.h	2017-05-27 11:44:06.733119794 +0000
++++ b/tools/profiler/core/platform.h	2017-05-27 11:46:16.004253520 +0000
+@@ -54,10 +54,11 @@
+ #include <vector>
+ #include "StackTop.h"
+ 
+-// We need a definition of gettid(), but old glibc versions don't provide a
+-// wrapper for it.
+-#if defined(__GLIBC__)
++// We need a definition of gettid(), but Linux libc implementations don't
++// provide a wrapper for it (except for Bionic)
++#if defined(__linux__)
+ #  include <unistd.h>
++#if !defined(__BIONIC__)
+ #  include <sys/syscall.h>
+ #  define gettid() static_cast<pid_t>(syscall(SYS_gettid))
++#endif
+@@ -71,6 +72,7 @@
+   return (pid_t) syscall(SYS_thread_selfid);
+ }
+ #endif
++#endif
+ 
+ #ifdef XP_WIN
+ #include <windows.h>
diff --git a/testing/firefox/sources b/testing/firefox/sources
index 97b3fcd7..d6fbce80 100644
--- a/testing/firefox/sources
+++ b/testing/firefox/sources
@@ -7,4 +7,5 @@ patches/fix-seccomp-bpf.patch
 patches/fix-toolkit.patch
 patches/fix-tools.patch
 patches/fix-webrtc-glibcisms.patch
+patches/fix-bug-1261392.patch
 patches/mallinfo.patch