diff --git a/build/BUILD.gn b/build/BUILD.gn
index 1adba35..8ce649c 100644
--- a/build/BUILD.gn
+++ b/build/BUILD.gn
@@ -39,6 +39,9 @@
     "//inc",
     "//inc/vmapi",
     "//src/arch/${plat_arch}/inc",
+
+    # Auto-generated headers using the 'offset_size_header' build rule.
+    "${root_gen_dir}/offset_size_header",
   ]
 
   defines = [
diff --git a/build/toolchain/embedded.gni b/build/toolchain/embedded.gni
index 476873c..31f7894 100644
--- a/build/toolchain/embedded.gni
+++ b/build/toolchain/embedded.gni
@@ -78,6 +78,15 @@
       ]
     }
 
+    tool("alink") {
+      outfile = "{{target_out_dir}}/{{target_output_name}}.a"
+      command = "rm -f $outfile && ${invoker.ar} -rc $outfile {{inputs}}"
+      description = "ALINK $outfile"
+      outputs = [
+        outfile,
+      ]
+    }
+
     tool("stamp") {
       command = "touch {{output}}"
       description = "STAMP {{output}}"
@@ -108,6 +117,7 @@
   embedded_cc_toolchain(target_name) {
     cc = "clang"
     ld = "ld.lld"
+    ar = "llvm-ar"
 
     forward_variables_from(invoker,
                            [
@@ -149,6 +159,7 @@
   embedded_cc_toolchain(target_name) {
     cc = "clang"
     ld = "${invoker.tool_prefix}ld.bfd"
+    ar = "llvm-ar"
 
     forward_variables_from(invoker,
                            [
diff --git a/build/toolchain/gen_offset_size_header.py b/build/toolchain/gen_offset_size_header.py
new file mode 100755
index 0000000..f9e73cb
--- /dev/null
+++ b/build/toolchain/gen_offset_size_header.py
@@ -0,0 +1,62 @@
+#!/usr/bin/env python
+#
+# Copyright 2019 The Hafnium Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+#!/usr/bin/env python
+"""Generate a header file with definitions of constants parsed from a binary."""
+
+import argparse
+import os
+import re
+import subprocess
+import sys
+
+HF_ROOT = os.path.dirname(os.path.dirname(os.path.dirname(__file__)))
+BINUTILS_ROOT = os.path.join(HF_ROOT, "prebuilts", "linux-x64", "gcc", "bin")
+STRINGS = os.path.join(BINUTILS_ROOT, "aarch64-linux-android-strings")
+
+PROLOGUE = """
+/**
+ * This file was auto-generated by {}.
+ * Changes will be overwritten.
+ */
+
+#pragma once
+
+""".format(__file__)
+
+def main():
+	parser = argparse.ArgumentParser()
+	parser.add_argument("bin_file",
+		help="binary file to be parsed for definitions of constants")
+        parser.add_argument("out_file", help="output file");
+	args = parser.parse_args()
+
+	# Regex for finding definitions: <HAFNIUM_DEFINE name #value />
+	regex = re.compile(r'<HAFNIUM_DEFINE\s([A-Za-z0-9_]+)\s#([0-9]+) />')
+
+	# Extract strings from the input binary file.
+	stdout = subprocess.check_output([ STRINGS, args.bin_file ])
+	stdout = str(stdout).split(os.linesep)
+
+	with open(args.out_file, "w") as f:
+		f.write(PROLOGUE)
+		for line in stdout:
+			for match in regex.findall(line):
+				f.write("#define {} ({})\n".format(
+					match[0], match[1]))
+
+if __name__ == "__main__":
+    sys.exit(main())
diff --git a/build/toolchain/offset_size_header.gni b/build/toolchain/offset_size_header.gni
new file mode 100644
index 0000000..b409284
--- /dev/null
+++ b/build/toolchain/offset_size_header.gni
@@ -0,0 +1,84 @@
+# Copyright 2019 The Hafnium Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# This template auto-generate a C header file with "#define" constants, e.g.
+# struct sizes and member offsets.
+#
+# It uses a trick similar to other projects, e.g. Linux, where the integer
+# constant is used as an immediate in an inline assembly block. The source file
+# is compiled and the constant extracted by a script which generates the header
+# file. For easy grep-ing, the constant is compiled into a '.ascii' string,
+# surrounded by magic strings, and extracted using the 'strings' binutils tool.
+#
+# To guarantee correctness, the same source file is compiled again as part
+# of the parent target but this time the declarations are converted to
+# static_asserts to check the values at its compile-time.
+template("offset_size_header") {
+  target_lib = "${target_name}__lib"
+  target_header = "${target_name}__header"
+
+  # Compile source files into binaries that contain strings with definitions
+  # of constants.
+  static_library(target_lib) {
+    forward_variables_from(invoker,
+                           [
+                             "sources",
+                             "deps",
+                             "test_only",
+                           ])
+    defines = [ "GENERATE_BINARY" ]
+
+    # Disable LTO to force emitting assembly.
+    cflags = [ "-fno-lto" ]
+  }
+
+  # Extract strings from the static library, parse definitions and generate
+  # a header file.
+  action(target_header) {
+    forward_variables_from(invoker, [ "test_only" ])
+    lib_file = "${target_out_dir}/${target_lib}.a"
+    out_file = "${root_gen_dir}/offset_size_header/${invoker.path}"
+
+    script = "//build/toolchain/gen_offset_size_header.py"
+    args = [
+      rebase_path(lib_file, root_build_dir),
+      rebase_path(out_file, root_build_dir),
+    ]
+    deps = [
+      ":$target_lib",
+    ]
+    outputs = [
+      out_file,
+    ]
+  }
+
+  # This source_set will be compiled into the target that depends on this one.
+  # This generates static_asserts which check the constants in the generated
+  # header against compile-time structs.
+  source_set(target_name) {
+    forward_variables_from(invoker,
+                           [
+                             "sources",
+                             "test_only",
+                           ])
+    cflags = [
+      "-include",
+      invoker.path,
+    ]
+    defines = [ "VERIFY_HEADER" ]
+    deps = [
+      ":$target_header",
+    ]
+  }
+}
diff --git a/inc/hf/offset_size_header.h b/inc/hf/offset_size_header.h
new file mode 100644
index 0000000..7d96950
--- /dev/null
+++ b/inc/hf/offset_size_header.h
@@ -0,0 +1,78 @@
+/*
+ * Copyright 2019 The Hafnium Authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * This header file is intended for use by files compiled with the
+ * 'offset_size_header' build rule. See overview in 'offset_size_header.gni'.
+ */
+
+#pragma once
+
+#if (defined GENERATE_BINARY) && (defined VERIFY_HEADER)
+#error Only one action can be specified
+
+#elif defined GENERATE_BINARY
+
+/**
+ * File being compiled to generate binaries with definitions of constants.
+ */
+
+/**
+ * Emit a function with an embedded string in the format:
+ *     <HAFNIUM_DEFINE name #value />
+ * These will be recognized by a script that generates the header file.
+ */
+#define DEFINE(sym, val)                                    \
+	void gen_header__##sym(void)                        \
+	{                                                   \
+		__asm__ volatile(                           \
+			"\n"                                \
+			".ascii \"\\n<HAFNIUM_DEFINE " #sym \
+			" %0 />\\n\"\n"                     \
+			".align 8\n" /* Align epilogue */   \
+			:                                   \
+			: "i"(val));                        \
+	}
+
+#define DEFINE_SIZEOF(sym, type) DEFINE(sym, sizeof(type))
+#define DEFINE_OFFSETOF(sym, type, field) DEFINE(sym, offsetof(type, field))
+
+#elif defined VERIFY_HEADER
+
+/**
+ * File being compiled as part of the main build to check the values in
+ * the auto-generated header file (included using a command-line flag).
+ */
+
+#include "hf/static_assert.h"
+
+#define DEFINE_SIZEOF(sym, type)                                 \
+	void gen_header__##sym(void)                             \
+	{                                                        \
+		static_assert(sizeof(type) == sym,               \
+			      "Generated struct size mismatch"); \
+	}
+
+#define DEFINE_OFFSETOF(sym, type, field)                          \
+	void gen_header__##sym(void)                               \
+	{                                                          \
+		static_assert(offsetof(type, field) == sym,        \
+			      "Generated struct offset mismatch"); \
+	}
+
+#else
+#error No action specified
+#endif
diff --git a/src/arch/aarch64/hypervisor/BUILD.gn b/src/arch/aarch64/hypervisor/BUILD.gn
index c1ac799..0972dde 100644
--- a/src/arch/aarch64/hypervisor/BUILD.gn
+++ b/src/arch/aarch64/hypervisor/BUILD.gn
@@ -12,6 +12,15 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import("//build/toolchain/offset_size_header.gni")
+
+offset_size_header("offsets") {
+  sources = [
+    "offsets.c",
+  ]
+  path = "hf/arch/offsets.h"
+}
+
 # Hypervisor specific code.
 source_set("hypervisor") {
   public_configs = [ "//src/arch/aarch64:config" ]
@@ -24,13 +33,13 @@
   sources += [
     "debug_el1.c",
     "handler.c",
-    "offsets.c",
     "perfmon.c",
     "psci_handler.c",
     "sysregs.c",
   ]
 
   deps = [
+    ":offsets",
     "//src/arch/aarch64:arch",
     "//src/arch/aarch64:entry",
     "//src/arch/aarch64:smc",
diff --git a/src/arch/aarch64/hypervisor/exceptions.S b/src/arch/aarch64/hypervisor/exceptions.S
index e8e391b..b8a1fcd 100644
--- a/src/arch/aarch64/hypervisor/exceptions.S
+++ b/src/arch/aarch64/hypervisor/exceptions.S
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-#include "offsets.h"
+#include "hf/arch/offsets.h"
 #include "exception_macros.S"
 
 /**
diff --git a/src/arch/aarch64/hypervisor/hypervisor_entry.S b/src/arch/aarch64/hypervisor/hypervisor_entry.S
index ce76aa5..5867805 100644
--- a/src/arch/aarch64/hypervisor/hypervisor_entry.S
+++ b/src/arch/aarch64/hypervisor/hypervisor_entry.S
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-#include "offsets.h"
+#include "hf/arch/offsets.h"
 
 /**
  * Called only on first boot after the image has been relocated and BSS zeroed.
diff --git a/src/arch/aarch64/hypervisor/offsets.c b/src/arch/aarch64/hypervisor/offsets.c
index 1f32581..b99273c 100644
--- a/src/arch/aarch64/hypervisor/offsets.c
+++ b/src/arch/aarch64/hypervisor/offsets.c
@@ -14,24 +14,15 @@
  * limitations under the License.
  */
 
-#include "offsets.h"
-
 #include "hf/cpu.h"
-#include "hf/static_assert.h"
+#include "hf/offset_size_header.h"
 
-#define CHECK_OFFSET(name, type, field) \
-	CHECK_OFFSET_1(#name, name, offsetof(type, field))
-#define CHECK_OFFSET_1(name, actual, expected)               \
-	static_assert((actual) == (expected),                \
-		      "Offset " name " should be " #expected \
-		      " and not " #actual)
+DEFINE_OFFSETOF(CPU_ID, struct cpu, id)
+DEFINE_OFFSETOF(CPU_STACK_BOTTOM, struct cpu, stack_bottom)
+DEFINE_OFFSETOF(VCPU_REGS, struct vcpu, regs)
+DEFINE_OFFSETOF(VCPU_LAZY, struct vcpu, regs.lazy)
+DEFINE_OFFSETOF(VCPU_FREGS, struct vcpu, regs.fp)
 
-CHECK_OFFSET(CPU_ID, struct cpu, id);
-CHECK_OFFSET(CPU_STACK_BOTTOM, struct cpu, stack_bottom);
-CHECK_OFFSET(VCPU_REGS, struct vcpu, regs);
-CHECK_OFFSET(VCPU_LAZY, struct vcpu, regs.lazy);
-CHECK_OFFSET(VCPU_FREGS, struct vcpu, regs.fp);
-
-#ifdef VCPU_GIC
-CHECK_OFFSET(VCPU_GIC, struct vcpu, regs.gic);
+#if GIC_VERSION == 3 || GIC_VERSION == 4
+DEFINE_OFFSETOF(VCPU_GIC, struct vcpu, regs.gic)
 #endif
diff --git a/src/arch/aarch64/hypervisor/offsets.h b/src/arch/aarch64/hypervisor/offsets.h
deleted file mode 100644
index cc2621b..0000000
--- a/src/arch/aarch64/hypervisor/offsets.h
+++ /dev/null
@@ -1,28 +0,0 @@
-/*
- * Copyright 2018 The Hafnium Authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     https://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#pragma once
-
-/* These are checked in offset.c. */
-#define CPU_ID 0
-#define CPU_STACK_BOTTOM 8
-#define VCPU_REGS 32
-#define VCPU_LAZY (VCPU_REGS + 264)
-#define VCPU_FREGS (VCPU_LAZY + 280)
-
-#if GIC_VERSION == 3 || GIC_VERSION == 4
-#define VCPU_GIC (VCPU_FREGS + 528)
-#endif