diff --git a/rs_bindings_from_cc/BUILD b/rs_bindings_from_cc/BUILD
index 439360f6f..0934168bb 100644
--- a/rs_bindings_from_cc/BUILD
+++ b/rs_bindings_from_cc/BUILD
@@ -43,6 +43,10 @@ _PROFILING_RUSTC_FLAGS = select({
     "//conditions:default": [],
 })
 
+# Undefine NDEBUG to ensure assertions (including inlined Clang AST assertions)
+# remain active even in opt compilation mode (see b/541930690).
+_CRUBIT_COPTS = ["-UNDEBUG"]
+
 rust_bindings_from_cc_binary(
     name = "rs_bindings_from_cc",
     binary = ":rs_bindings_from_cc_main",
@@ -93,6 +97,7 @@ crubit_rust_binary(
 cc_library(
     name = "rs_bindings_from_cc_impl",
     srcs = ["rs_bindings_from_cc.cc"],
+    copts = _CRUBIT_COPTS,
     # Defines CRUBIT_HEAP_PROFILING when --define=enable_heap_profiling=1 is passed,
     # enabling heap profile recording in rs_bindings_from_cc.cc.
     defines = select({
@@ -123,6 +128,7 @@ cc_library(
     name = "generate_bindings_and_metadata",
     srcs = ["generate_bindings_and_metadata.cc"],
     hdrs = ["generate_bindings_and_metadata.h"],
+    copts = _CRUBIT_COPTS,
     visibility = [
         "//cargo:__subpackages__",
     ],
@@ -181,6 +187,7 @@ cc_library(
     name = "ast_util",
     srcs = ["ast_util.cc"],
     hdrs = ["ast_util.h"],
+    copts = _CRUBIT_COPTS,
     visibility = ["//:__subpackages__"],
     deps = [
         ":cc_ir",
@@ -224,6 +231,7 @@ cc_library(
     name = "type_map",
     srcs = ["type_map.cc"],
     hdrs = ["type_map.h"],
+    copts = _CRUBIT_COPTS,
     visibility = ["//:__subpackages__"],
     deps = [
         ":cc_ir",
@@ -237,6 +245,7 @@ cc_library(
     name = "annotations_consumer",
     srcs = ["annotations_consumer.cc"],
     hdrs = ["annotations_consumer.h"],
+    copts = _CRUBIT_COPTS,
     deps = [
         ":cc_ir",
         "//common:annotation_reader",
@@ -252,6 +261,7 @@ cc_library(
     name = "cmdline",
     srcs = ["cmdline.cc"],
     hdrs = ["cmdline.h"],
+    copts = _CRUBIT_COPTS,
     visibility = [
         "//cargo:__subpackages__",
     ],
@@ -277,6 +287,7 @@ cc_library(
 cc_library(
     name = "cmdline_flags",
     hdrs = ["cmdline_flags.h"],
+    copts = _CRUBIT_COPTS,
     deps = [
         "@abseil-cpp//absl/flags:flag",
         "@abseil-cpp//absl/strings:string_view",
@@ -305,6 +316,7 @@ crubit_cc_test(
 cc_library(
     name = "decl_importer",
     hdrs = ["decl_importer.h"],
+    copts = _CRUBIT_COPTS,
     visibility = ["//:__subpackages__"],
     deps = [
         "cc_ir",
@@ -332,6 +344,7 @@ cc_library(
     name = "frontend_action",
     srcs = ["frontend_action.cc"],
     hdrs = ["frontend_action.h"],
+    copts = _CRUBIT_COPTS,
     deps = [
         ":ast_consumer",
         ":decl_importer",
@@ -346,6 +359,7 @@ cc_library(
     name = "ast_consumer",
     srcs = ["ast_consumer.cc"],
     hdrs = ["ast_consumer.h"],
+    copts = _CRUBIT_COPTS,
     deps = [
         ":decl_importer",
         ":importer",
@@ -359,6 +373,7 @@ cc_library(
     name = "importer",
     srcs = ["importer.cc"],
     hdrs = ["importer.h"],
+    copts = _CRUBIT_COPTS,
     deps = [
         ":annotations_consumer",
         ":ast_util",
@@ -444,6 +459,7 @@ cc_library(
     name = "cc_ir",
     srcs = ["ir.cc"],
     hdrs = ["ir.h"],
+    copts = _CRUBIT_COPTS,
     visibility = ["//:__subpackages__"],
     deps = [
         ":bazel_types",
@@ -539,6 +555,7 @@ cc_library(
     name = "ir_from_cc",
     srcs = ["ir_from_cc.cc"],
     hdrs = ["ir_from_cc.h"],
+    copts = _CRUBIT_COPTS,
     deps = [
         ":bazel_types",
         ":cc_ir",
@@ -568,6 +585,7 @@ cc_library(
     testonly = 1,
     srcs = ["ir_from_cc_dependency.cc"],
     hdrs = ["ir_from_cc_dependency.h"],
+    copts = _CRUBIT_COPTS,
     deps = [
         ":bazel_types",
         ":cc_ir",
@@ -584,6 +602,7 @@ cc_library(
     name = "proto_from_cc",
     testonly = 1,
     srcs = ["proto_from_cc.cc"],
+    copts = _CRUBIT_COPTS,
     deps = [
         ":cc_ir",
         ":cmdline_flags",
@@ -623,6 +642,7 @@ cc_library(
         "src_code_gen_ffi_serialized_proto.cc",
     ],
     hdrs = ["src_code_gen_ffi.h"],
+    copts = _CRUBIT_COPTS,
     deps = [
         ":profiling",
         "//common:cc_ffi_types",
@@ -650,6 +670,7 @@ cc_library(
     name = "src_code_gen",
     srcs = ["src_code_gen.cc"],
     hdrs = ["src_code_gen.h"],
+    copts = _CRUBIT_COPTS,
     deps = [
         ":cc_ir",
         ":profiling",
@@ -667,6 +688,7 @@ cc_library(
     name = "ast_convert",
     srcs = ["ast_convert.cc"],
     hdrs = ["ast_convert.h"],
+    copts = _CRUBIT_COPTS,
     visibility = ["//:__subpackages__"],
     deps = [
         ":ast_util",
@@ -686,6 +708,7 @@ cc_library(
     name = "recording_diagnostic_consumer",
     srcs = ["recording_diagnostic_consumer.cc"],
     hdrs = ["recording_diagnostic_consumer.h"],
+    copts = _CRUBIT_COPTS,
     visibility = [
         "//:__subpackages__",
     ],
@@ -746,6 +769,7 @@ cc_library(
     name = "cc_collect_instantiations",
     srcs = ["collect_instantiations.cc"],
     hdrs = ["collect_instantiations.h"],
+    copts = _CRUBIT_COPTS,
     deps = [
         ":collect_instantiations",  # build_cleaner: keep
         "//common:cc_ffi_types",
@@ -797,6 +821,7 @@ cc_library(
     name = "collect_namespaces",
     srcs = ["collect_namespaces.cc"],
     hdrs = ["collect_namespaces.h"],
+    copts = _CRUBIT_COPTS,
     visibility = ["//:__subpackages__"],
     deps = [
         ":bazel_types",
diff --git a/rs_bindings_from_cc/importers/BUILD b/rs_bindings_from_cc/importers/BUILD
index 8689cc2e0..63fb15dac 100644
--- a/rs_bindings_from_cc/importers/BUILD
+++ b/rs_bindings_from_cc/importers/BUILD
@@ -8,10 +8,15 @@ package(
     default_visibility = ["//:__subpackages__"],
 )
 
+# Undefine NDEBUG to ensure assertions (including inlined Clang AST assertions)
+# remain active even in opt compilation mode (see b/541930690).
+_CRUBIT_COPTS = ["-UNDEBUG"]
+
 cc_library(
     name = "class_template",
     srcs = ["class_template.cc"],
     hdrs = ["class_template.h"],
+    copts = _CRUBIT_COPTS,
     deps = [
         "//rs_bindings_from_cc:cc_ir",
         "//rs_bindings_from_cc:decl_importer",
@@ -23,6 +28,7 @@ cc_library(
     name = "cxx_record",
     srcs = ["cxx_record.cc"],
     hdrs = ["cxx_record.h"],
+    copts = _CRUBIT_COPTS,
     deps = [
         "//common:annotation_reader",
         "//common:status_macros",
@@ -53,6 +59,7 @@ cc_library(
     name = "enum",
     srcs = ["enum.cc"],
     hdrs = ["enum.h"],
+    copts = _CRUBIT_COPTS,
     deps = [
         "//lifetime_annotations:type_lifetimes",
         "//rs_bindings_from_cc:ast_util",
@@ -70,6 +77,7 @@ cc_library(
     name = "enum_constant",
     srcs = ["enum_constant.cc"],
     hdrs = ["enum_constant.h"],
+    copts = _CRUBIT_COPTS,
     deps = [
         "//rs_bindings_from_cc:ast_util",
         "//rs_bindings_from_cc:cc_ir",
@@ -85,6 +93,7 @@ cc_library(
     name = "var",
     srcs = ["var.cc"],
     hdrs = ["var.h"],
+    copts = _CRUBIT_COPTS,
     deps = [
         "//rs_bindings_from_cc:ast_util",
         "//rs_bindings_from_cc:cc_ir",
@@ -100,6 +109,7 @@ cc_library(
     name = "friend",
     srcs = ["friend.cc"],
     hdrs = ["friend.h"],
+    copts = _CRUBIT_COPTS,
     deps = [
         "//rs_bindings_from_cc:cc_ir",
         "//rs_bindings_from_cc:decl_importer",
@@ -113,6 +123,7 @@ cc_library(
     name = "function",
     srcs = ["function.cc"],
     hdrs = ["function.h"],
+    copts = _CRUBIT_COPTS,
     deps = [
         "//common:annotation_reader",
         "//lifetime_annotations",
@@ -143,6 +154,7 @@ cc_library(
     name = "function_template",
     srcs = ["function_template.cc"],
     hdrs = ["function_template.h"],
+    copts = _CRUBIT_COPTS,
     deps = [
         "//rs_bindings_from_cc:cc_ir",
         "//rs_bindings_from_cc:decl_importer",
@@ -155,6 +167,7 @@ cc_library(
     name = "namespace",
     srcs = ["namespace.cc"],
     hdrs = ["namespace.h"],
+    copts = _CRUBIT_COPTS,
     deps = [
         "//rs_bindings_from_cc:ast_util",
         "//rs_bindings_from_cc:cc_ir",
@@ -168,6 +181,7 @@ cc_library(
     name = "type_alias",
     srcs = ["type_alias.cc"],
     hdrs = ["type_alias.h"],
+    copts = _CRUBIT_COPTS,
     deps = [
         "//lifetime_annotations:type_lifetimes",
         "//rs_bindings_from_cc:ast_util",
@@ -187,6 +201,7 @@ cc_library(
     name = "existing_rust_type",
     srcs = ["existing_rust_type.cc"],
     hdrs = ["existing_rust_type.h"],
+    copts = _CRUBIT_COPTS,
     deps = [
         "//common:annotation_reader",
         "//common:status_macros",