diff --git a/include/pub_tool_libcsetjmp.h b/include/pub_tool_libcsetjmp.h
index e9638c3..1a52715 100644
--- a/include/pub_tool_libcsetjmp.h
+++ b/include/pub_tool_libcsetjmp.h
@@ -150,6 +150,111 @@ UWord VG_MINIMAL_SETJMP(VG_MINIMAL_JMP_BUF(_env));
 __attribute__((noreturn))
 void VG_MINIMAL_LONGJMP(VG_MINIMAL_JMP_BUF(_env));
 
+#elif defined __aarch64__ && defined __clang__
+
+// __builtin_setjmp is not implemented by the standard C library
+// used on Android in current llvm-based toolchains as of NDK r19.
+//
+// Here is a custom implementation of Valgrind's "minimal" setjmp
+// interface. Per the comment at the top of this file, we only need
+// to save integer registers.
+//
+// Per the Procedure Call Standard for the ARM 64-bit Architecture
+// document,
+// http://infocenter.arm.com/help/topic/com.arm.doc.ihi0055b/IHI0055B_aapcs64.pdf
+// Section 5.1.1. General-purpose registers:
+// >
+// > A subroutine invocation must preserve the contents of the
+// > registers r19-r29 and SP."
+//
+// We also need to save and restore r30, the link register, i.e.
+// the default destination that a 'ret' instruction branches to.
+//
+// Note that this document is phrased in terms of 'r' registers
+// (e.g. "r30") because it aims to be agnostic as to A64 vs A32
+// instruction sets, but here we are targeting the A64 instruction
+// set, so we are dealing with 'x' registers.
+
+
+#define VG_MINIMAL_JMP_BUF(_name)        UWord _name [13]
+
+__attribute__((returns_twice))
+inline UWord VG_MINIMAL_SETJMP(VG_MINIMAL_JMP_BUF(_env))
+{
+   asm volatile(
+     // x9 is the first of the regular temporary registers
+     // per the above-mentioned Procedule Call Standard document.
+     // Use it as temporary to hold the value of SP, since str does
+     // not accept SP as operand.
+     "  mov x9, sp                     \n"
+     // Store the general-purpose registers that we need to save
+     // per the above discussion.
+     // Note that x30 is the link register.
+     "  stp x19, x20, [%[_env], 0]     \n"
+     "  stp x21, x22, [%[_env], 0x10]  \n"
+     "  stp x23, x24, [%[_env], 0x20]  \n"
+     "  stp x25, x26, [%[_env], 0x30]  \n"
+     "  stp x27, x28, [%[_env], 0x40]  \n"
+     "  stp x29, x30, [%[_env], 0x50]  \n"
+     // Store the value of SP.
+     "  str x9,       [%[_env], 0x60]  \n"
+     :
+     // No outputs
+     :
+     // Inputs
+     [_env]"r"(_env)
+     :
+     // Clobbers.
+     // We have used x9 as a temporary
+     "x9",
+     // We have written to memory locations
+     "memory");
+
+  // Direct invokation of setjmp always returns 0.
+  // The pseudo returning of the value 1 as a return from longjmp
+  // is implemented in longjmp.
+  return 0;
+}
+
+__attribute__((noreturn))
+inline void VG_MINIMAL_LONGJMP(VG_MINIMAL_JMP_BUF(_env))
+{
+   asm volatile(
+     // Loads to match the stores in the above setjmp implementation.
+     "  ldp x19, x20, [%[_env], 0]     \n"
+     "  ldp x21, x22, [%[_env], 0x10]  \n"
+     "  ldp x23, x24, [%[_env], 0x20]  \n"
+     "  ldp x25, x26, [%[_env], 0x30]  \n"
+     "  ldp x27, x28, [%[_env], 0x40]  \n"
+     "  ldp x29, x30, [%[_env], 0x50]  \n"
+     "  ldr x9,       [%[_env], 0x60]  \n"
+     "  mov sp, x9                     \n"
+     // return as setjmp for the second time, returning 1.
+     // Since we have loaded the link register x30 from the saved buffer
+     // that was set by the above setjmp implementation, the 'ret' instruction
+     // here is going to return to where setjmp was called.
+     // Per the setjmp/longjmp contract, that pseudo second returning
+     // of setjmp should return the value 1.
+     // x0 is holds the integer return value.
+     "  mov x0, 1                      \n"
+     "  ret                            \n"
+     :
+     // No outputs
+     :
+     // Inputs
+     [_env]"r"(_env)
+     :
+     // Clobbers.
+     // We have used x9 as a temporary
+     "x9");
+
+  // This statement is unreachable because the above asm statement
+  // unconditionally does a 'ret' instruction. The purpose of this
+  // statement is to silence clang warnings about this function returning
+  // while having the 'noreturn' attribute.
+  __builtin_unreachable();
+}
+
 #else
 
 /* The default implementation. */
diff --git a/include/pub_tool_libcsetjmp.h.orig b/include/pub_tool_libcsetjmp.h.orig
new file mode 100644
index 0000000..e9638c3
--- /dev/null
+++ b/include/pub_tool_libcsetjmp.h.orig
@@ -0,0 +1,166 @@
+
+/*--------------------------------------------------------------------*/
+/*--- A minimal setjmp/longjmp facility.     pub_tool_libcsetjmp.h ---*/
+/*--------------------------------------------------------------------*/
+
+/*
+   This file is part of Valgrind, a dynamic binary instrumentation
+   framework.
+
+   Copyright (C) 2010-2017 Mozilla Foundation
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License as
+   published by the Free Software Foundation; either version 2 of the
+   License, or (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, see <http://www.gnu.org/licenses/>.
+
+   The GNU General Public License is contained in the file COPYING.
+*/
+
+/* Contributed by Julian Seward <jseward@acm.org> */
+
+#ifndef __PUB_TOOL_LIBCSETJMP_H
+#define __PUB_TOOL_LIBCSETJMP_H
+
+#include "pub_tool_basics.h"   // UWord
+
+//--------------------------------------------------------------------
+// PURPOSE: Provides a minimal setjmp/longjmp facility, that saves/
+// restores integer registers, but not necessarily anything more.
+//--------------------------------------------------------------------
+
+
+/* This provides an extremely minimal setjmp/longjmp facility, in
+   which only the host's integer registers are saved/restored.  Or at
+   least, that is the minimal guaranteed functionality.
+
+   Until Apr 2011 we used __builtin_setjmp and __builtin_longjmp, but
+   it appears that that is not always correctly implemented.  See
+   https://bugs.kde.org/show_bug.cgi?id=259977.  So this module wraps
+   those functions up and facilitates replacing them with our own
+   implementations where necessary.
+*/
+
+/* --- !!! --- EXTERNAL HEADERS start --- !!! --- */
+#include <setjmp.h>
+/* --- !!! --- EXTERNAL HEADERS end --- !!! --- */
+
+
+/* Don't use jmp_buf, __builtin_setjmp or __builtin_longjmp directly.
+   They don't always work reliably.  Instead use these macros, which
+   provide the opportunity to supply alternative implementations as
+   necessary.
+
+   Note that the abstraction is done with macros (ick) rather than
+   functions and typedefs, since wrapping __builtin_setjmp up in a
+   second function (eg, VG_(minimal_setjmp)) doesn't seem to work for
+   whatever reason -- returns via a VG_(minimal_longjmp) go wrong.
+
+   VG_MINIMAL_SETJMP stores the current integer register state in the
+   supplied argument, and returns zero.  VG_MINIMAL_LONGJMP resumes
+   with the previously saved state, and returns a nonzero, word-sized
+   value.  The caller must test all bits of the value in order to make
+   a zero/non-zero determination.
+*/
+
+#if defined(VGP_ppc32_linux)
+
+#define VG_MINIMAL_JMP_BUF(_name)        UInt _name [32+1+1]
+__attribute__((returns_twice))
+UWord VG_MINIMAL_SETJMP(VG_MINIMAL_JMP_BUF(_env));
+__attribute__((noreturn))
+void  VG_MINIMAL_LONGJMP(VG_MINIMAL_JMP_BUF(_env));
+
+
+#elif defined(VGP_ppc64be_linux) || defined(VGP_ppc64le_linux)
+
+#define VG_MINIMAL_JMP_BUF(_name)        ULong _name [32+1+1]
+__attribute__((returns_twice))
+UWord VG_MINIMAL_SETJMP(VG_MINIMAL_JMP_BUF(_env));
+__attribute__((noreturn))
+void  VG_MINIMAL_LONGJMP(VG_MINIMAL_JMP_BUF(_env));
+
+
+#elif defined(VGP_amd64_linux) || defined(VGP_amd64_darwin) || \
+      defined(VGP_amd64_solaris) || defined(VGP_amd64_freebsd)
+
+#define VG_MINIMAL_JMP_BUF(_name)        ULong _name [16+1]
+__attribute__((returns_twice))
+UWord VG_MINIMAL_SETJMP(VG_MINIMAL_JMP_BUF(_env));
+__attribute__((noreturn))
+void  VG_MINIMAL_LONGJMP(VG_MINIMAL_JMP_BUF(_env));
+
+
+#elif defined(VGP_x86_linux) || defined(VGP_x86_darwin) || \
+      defined(VGP_x86_solaris) || defined(VGP_x86_freebsd)
+
+#define VG_MINIMAL_JMP_BUF(_name)        UInt _name [8+1]
+__attribute__((returns_twice))
+__attribute__((regparm(1))) // this is critical; don't delete
+UWord VG_MINIMAL_SETJMP(VG_MINIMAL_JMP_BUF(_env));
+__attribute__((noreturn))
+__attribute__((regparm(1))) // ditto
+void  VG_MINIMAL_LONGJMP(VG_MINIMAL_JMP_BUF(_env));
+
+#elif defined(VGP_mips32_linux) || defined(VGP_nanomips_linux)
+
+#define VG_MINIMAL_JMP_BUF(_name)        ULong _name [104 / sizeof(ULong)]
+__attribute__((returns_twice))
+UWord VG_MINIMAL_SETJMP(VG_MINIMAL_JMP_BUF(_env));
+__attribute__((noreturn))
+void  VG_MINIMAL_LONGJMP(VG_MINIMAL_JMP_BUF(_env));
+
+#elif defined(VGP_mips64_linux)
+
+#define VG_MINIMAL_JMP_BUF(_name)        ULong _name [168 / sizeof(ULong)]
+__attribute__((returns_twice))
+UWord VG_MINIMAL_SETJMP(VG_MINIMAL_JMP_BUF(_env));
+__attribute__((noreturn))
+void  VG_MINIMAL_LONGJMP(VG_MINIMAL_JMP_BUF(_env));
+
+#elif defined(VGP_s390x_linux)
+
+#define VG_MINIMAL_JMP_BUF(_name)        ULong _name [10 + 8]
+__attribute__((returns_twice))
+UWord VG_MINIMAL_SETJMP(VG_MINIMAL_JMP_BUF(_env));
+__attribute__((noreturn))
+void  VG_MINIMAL_LONGJMP(VG_MINIMAL_JMP_BUF(_env));
+
+#elif defined(__clang__) && defined(VGP_arm64_linux)
+
+#define VG_MINIMAL_JMP_BUF(_name)        UWord _name [13]
+__attribute__((returns_twice))
+UWord VG_MINIMAL_SETJMP(VG_MINIMAL_JMP_BUF(_env));
+__attribute__((noreturn))
+void VG_MINIMAL_LONGJMP(VG_MINIMAL_JMP_BUF(_env));
+
+#elif defined(VGP_arm64_freebsd)
+
+#define VG_MINIMAL_JMP_BUF(_name)        UWord _name [22]
+__attribute__((returns_twice))
+UWord VG_MINIMAL_SETJMP(VG_MINIMAL_JMP_BUF(_env));
+__attribute__((noreturn))
+void VG_MINIMAL_LONGJMP(VG_MINIMAL_JMP_BUF(_env));
+
+#else
+
+/* The default implementation. */
+#define VG_MINIMAL_JMP_BUF(_name) jmp_buf _name
+#define VG_MINIMAL_SETJMP(_env)   ((UWord)(__builtin_setjmp((_env))))
+#define VG_MINIMAL_LONGJMP(_env)  __builtin_longjmp((_env),1)
+
+#endif
+
+#endif   // __PUB_TOOL_LIBCSETJMP_H
+
+/*--------------------------------------------------------------------*/
+/*--- end                                    pub_tool_libcsetjmp.h ---*/
+/*--------------------------------------------------------------------*/
-- 
2.48.1