diff --git a/hw/ip/otbn/util/otbn_as.py b/hw/ip/otbn/util/otbn_as.py
index 3cf505a..959fd2c 100755
--- a/hw/ip/otbn/util/otbn_as.py
+++ b/hw/ip/otbn/util/otbn_as.py
@@ -1187,10 +1187,9 @@
         return 127
 
 
-def main() -> int:
-    files, other_args, flags = parse_positionals(sys.argv)
+def main(argv: List[str]) -> int:
+    files, other_args, flags = parse_positionals(argv)
     files = files or ['--']
-
     just_translate = '--otbn-translate' in flags
 
     # files is now a nonempty list of input files. Rather unusually, '--'
@@ -1246,4 +1245,4 @@
 
 
 if __name__ == '__main__':
-    sys.exit(main())
+    sys.exit(main(sys.argv))
diff --git a/meson.build b/meson.build
index 0c2d8af..f78a963 100644
--- a/meson.build
+++ b/meson.build
@@ -209,6 +209,7 @@
 prog_objdump = find_program('objdump')
 prog_objcopy = find_program('objcopy')
 
+path_otbn_tools = meson.project_source_root() / 'hw/ip/otbn/util/'
 prog_otbn_as = meson.project_source_root() / 'hw/ip/otbn/util/otbn_as.py'
 prog_otbn_ld = meson.project_source_root() / 'hw/ip/otbn/util/otbn_ld.py'
 
@@ -286,6 +287,8 @@
   'PYTHON=@0@'.format(prog_python.full_path()),
   'OTBN_AS=@0@'.format(prog_otbn_as),
   'OTBN_LD=@0@'.format(prog_otbn_ld),
+  'OTBN_TOOLS=@0@'.format(path_otbn_tools),
+  'OTBN_LD=@0@'.format(prog_otbn_ld),
   'RV32_TOOL_OBJCOPY=@0@'.format(prog_objcopy.full_path()),
   'RV32_TOOL_AS=@0@'.format(prog_as.full_path()),
   'RV32_TOOL_LD=@0@'.format(prog_ld.full_path()),
diff --git a/rules/otbn.bzl b/rules/otbn.bzl
index ab53206..2cc12e4 100644
--- a/rules/otbn.bzl
+++ b/rules/otbn.bzl
@@ -100,9 +100,8 @@
                   [ctx.executable._otbn_as] +
                   ctx.files._otbn_ld +
                   ctx.files._otbn_data +
-                  ctx.files._wrapper),
+                  [ctx.executable._wrapper]),
         env = {
-            "OTBN_AS": ctx.executable._otbn_as.path,
             "OTBN_LD": ctx.file._otbn_ld.path,
             "RV32_TOOL_AS": assembler.path,
             "RV32_TOOL_AR": cc_toolchain.ar_executable,
@@ -115,7 +114,7 @@
             "--no-assembler",
             "--out-dir={}".format(elf.dirname),
         ] + [obj.path for obj in (objs + deps)],
-        executable = ctx.file._wrapper,
+        executable = ctx.executable._wrapper,
     )
 
     feature_configuration = cc_common.configure_features(
@@ -189,8 +188,9 @@
             allow_files = True,
         ),
         "_wrapper": attr.label(
-            default = "//util:otbn_build.py",
-            allow_single_file = True,
+            default = "//util:otbn_build",
+            executable = True,
+            cfg = "exec",
         ),
     },
     fragments = ["cpp"],
diff --git a/sw/device/lib/crypto/meson.build b/sw/device/lib/crypto/meson.build
index 284cd64..a9f28ee 100644
--- a/sw/device/lib/crypto/meson.build
+++ b/sw/device/lib/crypto/meson.build
@@ -25,7 +25,7 @@
 
 otbn_build_command = [
   prog_env,
-  'OTBN_AS=@0@'.format(prog_otbn_as),
+  'OTBN_TOOLS=@0@'.format(path_otbn_tools),
   'OTBN_LD=@0@'.format(prog_otbn_ld),
   'RV32_TOOL_OBJCOPY=@0@'.format(prog_objcopy.full_path()),
   'RV32_TOOL_AS=@0@'.format(prog_as.full_path()),
diff --git a/sw/otbn/meson.build b/sw/otbn/meson.build
index 2540e38..0b0a034 100644
--- a/sw/otbn/meson.build
+++ b/sw/otbn/meson.build
@@ -45,7 +45,7 @@
 
 otbn_build_command = [
   prog_env,
-  'OTBN_AS=@0@'.format(prog_otbn_as),
+  'OTBN_TOOLS=@0@'.format(path_otbn_tools),
   'OTBN_LD=@0@'.format(prog_otbn_ld),
   'RV32_TOOL_OBJCOPY=@0@'.format(prog_objcopy.full_path()),
   'RV32_TOOL_AS=@0@'.format(prog_as.full_path()),
diff --git a/util/BUILD b/util/BUILD
index c02957a..34188a1 100644
--- a/util/BUILD
+++ b/util/BUILD
@@ -3,6 +3,7 @@
 # SPDX-License-Identifier: Apache-2.0
 
 load("@rules_python//python:defs.bzl", "py_binary")
+load("@ot_python_deps//:requirements.bzl", "requirement")
 
 package(default_visibility = ["//visibility:public"])
 
@@ -16,6 +17,16 @@
 )
 
 py_binary(
+    name = "otbn_build",
+    srcs = ["otbn_build.py"],
+    imports = ["../hw/ip/otbn/util/"],
+    deps = [
+        requirement("pyelftools"),
+        "//hw/ip/otbn/util:otbn_as",
+    ],
+)
+
+py_binary(
     name = "rom_chip_info",
     srcs = ["rom_chip_info.py"],
 )
diff --git a/util/otbn_build.py b/util/otbn_build.py
index 4453095..3e2d14d 100755
--- a/util/otbn_build.py
+++ b/util/otbn_build.py
@@ -15,7 +15,7 @@
   sensible default values are provided (tools are generally expected to be in
   the $PATH).
 
-  OTBN_AS            path to otbn_as.py, the OTBN assembler
+  OTBN_TOOLS         path to the OTBN linker and assemler tools
   OTBN_LD            path to otbn_ld.py, the OTBN linker
   RV32_TOOL_LD       path to RV32 ld
   RV32_TOOL_AS       path to RV32 as
@@ -48,6 +48,17 @@
 
 REPO_TOP = Path(__file__).parent.parent.resolve()
 
+# yapf: disable
+
+# TODO: remove with meson; bazel will set the PYTHONPATH to locate otbn
+# tool modules
+otbn_tools_path = os.environ.get('OTBN_TOOLS', None)
+if otbn_tools_path:
+    sys.path.append(otbn_tools_path)
+import otbn_as
+
+# yapf: enable
+
 
 def cmd_to_str(cmd: List[str]) -> str:
     return ' '.join([shlex.quote(str(a)) for a in cmd])
@@ -68,7 +79,7 @@
     subprocess.run(str_args, check=True)
 
 
-def run_tool(tool: str, out_file: Path, args) -> None:
+def run_tool(tool, out_file: Path, args) -> None:
     '''Run tool to produce out_file (using an '-o' argument)
 
     This works by writing to a temporary file (in the same directory) and then
@@ -83,8 +94,11 @@
                                           dir=out_dir,
                                           delete=False)
     try:
-        run_cmd([tool, '-o', tmpfile.name] + args,
-                cmd_to_str([tool, '-o', out_file] + args))
+        if type(tool) == str:
+            run_cmd([tool, '-o', tmpfile.name] + args,
+                    cmd_to_str([tool, '-o', out_file] + args))
+        else:
+            tool(['', '-o', tmpfile.name] + list(map(str, args)))
 
         # If we get here, the tool ran successfully, producing the output file.
         # Use os.replace to rename appropriately.
@@ -101,9 +115,7 @@
 
 
 def call_otbn_as(src_file: Path, out_file: Path):
-    otbn_as_cmd = os.environ.get('OTBN_AS',
-                                 str(REPO_TOP / 'hw/ip/otbn/util/otbn_as.py'))
-    run_tool(otbn_as_cmd, out_file, [src_file])
+    run_tool(otbn_as.main, out_file, [src_file])
 
 
 def call_otbn_ld(src_files: List[Path], out_file: Path,