diff --git a/install_dependencies.sh b/install_dependencies.sh
index 7e8a8657..907aba7a 100755
--- a/install_dependencies.sh
+++ b/install_dependencies.sh
@@ -1,17 +1,31 @@
 #!/bin/bash
 # Copyright 2021 Google LLC
 #
-# 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
+# Please read carefully before adding new dependencies:
+#
+# System dependencies are disallowed by default, and the bar for exceptions is
+# high.
+#
+# pins-infra strives for a hermetic build, i.e. one that is insensitive to the
+# libraries and other software installed on your machine, other than Bazel and
+# the compilers. This ensure the build is reproducible and portable.
+#
+# Before adding a new system dependency, consider the following:
 #
-#      http://www.apache.org/licenses/LICENSE-2.0
+# 1. Please read the note on dependencies in pins_infra_deps.bzl.
 #
-# 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.
+# 2. Can the dependency be avoided altogether? Consider that there is a
+#    non-trival cost to maintaining dependencies over time.
+#
+# 3. Can the dependency be built with Bazel instead?
+#   - For many libraries, there are existing Bazel BUILD files. Try a quick
+#     Google search.
+#   - If there is no existing BUILD file, can you write your own BUILD file?
+#     See the bazel/ folder for examples. Ideally, we strive to upstream such
+#     BUILD files so everyone can benefit and share the maintenance burden.
+#   - If it's too hard to write a native BUILD file, try writing a BUILD file
+#     using rules_foreign_cc (https://github.com/bazelbuild/rules_foreign_cc).
+#.    See the bazel/ folder for examples.
 
 # Please read carefully before adding new dependencies:
 #
diff --git a/p4_symbolic/BUILD.bazel b/p4_symbolic/BUILD.bazel
index 753fa143..2fb1ac2d 100644
--- a/p4_symbolic/BUILD.bazel
+++ b/p4_symbolic/BUILD.bazel
@@ -14,11 +14,6 @@
 
 # This file contains build rules for the main binary of p4_symbolic.
 
-load("@bazel_skylib//rules:build_test.bzl", "build_test")
-load("//p4_pdpi/testing:diff_test.bzl", "cmd_diff_test", "diff_test")
-load("//p4_pdpi:pdgen.bzl", "p4_pd_proto")
-load("@com_github_p4lang_p4c//:bazel/p4_library.bzl", "p4_library")
-
 package(
     default_visibility = ["//visibility:public"],
     licenses = ["notice"],
@@ -29,8 +24,6 @@ cc_binary(
     srcs = [
         "main.cc",
     ],
-    # linkopts = ["-lz3"],
-    visibility = ["//p4_symbolic/symbolic:__pkg__"],
     deps = [
         ":parser",
         "//gutil:status",
@@ -49,15 +42,10 @@ cc_binary(
 
 cc_library(
     name = "parser",
-    srcs = [
-        "parser.cc",
-    ],
-    hdrs = [
-        "parser.h",
-    ],
-    visibility = ["//visibility:public"],
+    srcs = ["parser.cc"],
+    hdrs = ["parser.h"],
     deps = [
-	 "//gutil:proto",
+	"//gutil:proto",
         "//gutil:status",
 	"//p4_pdpi:ir_cc_proto",
         "//p4_symbolic/bmv2",
@@ -74,7 +62,6 @@ cc_library(
     name = "z3_util",
     srcs = ["z3_util.cc"],
     hdrs = ["z3_util.h"],
-    visibility = ["//visibility:public"],
     deps = [
         "//gutil:status",
         "//p4_pdpi/string_encodings:hex_string",
diff --git a/p4_symbolic/bmv2/BUILD.bazel b/p4_symbolic/bmv2/BUILD.bazel
index bfe70047..f80130ff 100644
--- a/p4_symbolic/bmv2/BUILD.bazel
+++ b/p4_symbolic/bmv2/BUILD.bazel
@@ -12,10 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-load("@bazel_skylib//rules:build_test.bzl", "build_test")
-load("//p4_pdpi/testing:diff_test.bzl", "cmd_diff_test", "diff_test")
-load("//p4_pdpi:pdgen.bzl", "p4_pd_proto")
-load("@com_github_p4lang_p4c//:bazel/p4_library.bzl", "p4_library")
 load("//p4_symbolic/bmv2:test.bzl", "bmv2_protobuf_parsing_test")
 
 package(
@@ -25,7 +21,6 @@ package(
 
 cc_proto_library(
     name = "bmv2_cc_proto",
-    visibility = ["//p4_symbolic:__subpackages__"],
     deps = [":bmv2_proto"],
 )
 
@@ -34,7 +29,6 @@ proto_library(
     srcs = [
         "bmv2.proto",
     ],
-    visibility = ["//p4_symbolic:__subpackages__"],
     deps = [
         "@com_google_protobuf//:struct_proto",
     ],
@@ -48,7 +42,6 @@ cc_library(
     hdrs = [
         "bmv2.h",
     ],
-    visibility = ["//p4_symbolic:__subpackages__"],
     deps = [
         ":bmv2_cc_proto",
         "//gutil:status",
diff --git a/p4_symbolic/ir/BUILD.bazel b/p4_symbolic/ir/BUILD.bazel
index 26f11de1..be4ec3e5 100644
--- a/p4_symbolic/ir/BUILD.bazel
+++ b/p4_symbolic/ir/BUILD.bazel
@@ -12,10 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-load("@bazel_skylib//rules:build_test.bzl", "build_test")
-load("//p4_pdpi/testing:diff_test.bzl", "cmd_diff_test", "diff_test")
-load("//p4_pdpi:pdgen.bzl", "p4_pd_proto")
-load("@com_github_p4lang_p4c//:bazel/p4_library.bzl", "p4_library")
 load("//p4_symbolic/ir:test.bzl", "ir_parsing_test")
 
 package(
@@ -23,6 +19,20 @@ package(
     licenses = ["notice"],
 )
 
+cc_proto_library(
+    name = "ir_cc_proto",
+    deps = [":ir_proto"],
+)
+
+proto_library(
+    name = "ir_proto",
+    srcs = ["ir.proto"],
+    deps = [
+        "//p4_pdpi:ir_proto",
+        "//p4_symbolic/bmv2:bmv2_proto",
+    ],
+)
+
 cc_library(
     name = "pdpi_driver",
     srcs = [
@@ -31,7 +41,6 @@ cc_library(
     hdrs = [
         "pdpi_driver.h",
     ],
-    visibility = ["//p4_symbolic:__subpackages__"],
     deps = [
         "//gutil:proto",
         "//gutil:status",
@@ -40,21 +49,6 @@ cc_library(
     ],
 )
 
-cc_proto_library(
-    name = "ir_cc_proto",
-    visibility = ["//p4_symbolic:__subpackages__"],
-    deps = [":ir_proto"],
-)
-
-proto_library(
-    name = "ir_proto",
-    srcs = ["ir.proto"],
-    deps = [
-        "//p4_pdpi:ir_proto",
-        "//p4_symbolic/bmv2:bmv2_proto",
-    ],
-)
-
 cc_library(
     name = "table_entries",
     srcs = [
@@ -63,7 +57,6 @@ cc_library(
     hdrs = [
         "table_entries.h",
     ],
-    visibility = ["//p4_symbolic:__subpackages__"],
     deps = [
         ":ir_cc_proto",
         "//gutil:status",
@@ -85,7 +78,6 @@ cc_library(
     hdrs = [
         "ir.h",
     ],
-    visibility = ["//p4_symbolic:__subpackages__"],
     deps = [
         ":ir_cc_proto",
         ":table_entries",
diff --git a/p4_symbolic/sai/BUILD.bazel b/p4_symbolic/sai/BUILD.bazel
index 93d15ead..f6bbff33 100644
--- a/p4_symbolic/sai/BUILD.bazel
+++ b/p4_symbolic/sai/BUILD.bazel
@@ -12,12 +12,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-load("@bazel_skylib//rules:build_test.bzl", "build_test")
-load("//p4_pdpi/testing:diff_test.bzl", "cmd_diff_test", "diff_test")
-load("//p4_pdpi:pdgen.bzl", "p4_pd_proto")
-load("@com_github_p4lang_p4c//:bazel/p4_library.bzl", "p4_library")
-
-package(licenses = ["notice"])
+package(
+    default_visibility = ["//visibility:public"],
+    licenses = ["notice"],
+)
 
 cc_library(
     name = "fields",
@@ -36,7 +34,6 @@ cc_library(
     name = "parser",
     srcs = ["parser.cc"],
     hdrs = ["parser.h"],
-    visibility = ["//p4_symbolic:__subpackages__"],
     deps = [
         ":fields",
         "//gutil:status",
diff --git a/p4_symbolic/symbolic/BUILD.bazel b/p4_symbolic/symbolic/BUILD.bazel
index 7dbad4ae..ca48e2b2 100644
--- a/p4_symbolic/symbolic/BUILD.bazel
+++ b/p4_symbolic/symbolic/BUILD.bazel
@@ -12,10 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-load("@bazel_skylib//rules:build_test.bzl", "build_test")
-load("//p4_pdpi/testing:diff_test.bzl", "cmd_diff_test", "diff_test")
-load("//p4_pdpi:pdgen.bzl", "p4_pd_proto")
-load("@com_github_p4lang_p4c//:bazel/p4_library.bzl", "p4_library")
 load("//p4_symbolic/symbolic:test.bzl", "end_to_end_test")
 
 package(
@@ -49,7 +45,6 @@ cc_library(
         "util.h",
         "values.h",
     ],
-    visibility = ["//p4_symbolic:__subpackages__"],
     deps = [
         "//gutil:status",
         "//p4_pdpi:ir_cc_proto",
diff --git a/p4_symbolic/testdata/BUILD.bazel b/p4_symbolic/testdata/BUILD.bazel
index 7ec79468..52e61f67 100644
--- a/p4_symbolic/testdata/BUILD.bazel
+++ b/p4_symbolic/testdata/BUILD.bazel
@@ -12,11 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-load("@bazel_skylib//rules:build_test.bzl", "build_test")
-load("//p4_pdpi/testing:diff_test.bzl", "cmd_diff_test", "diff_test")
-load("//p4_pdpi:pdgen.bzl", "p4_pd_proto")
-load("@com_github_p4lang_p4c//:bazel/p4_library.bzl", "p4_library")
-
 package(default_visibility = ["//visibility:public"])
 
 # Make sure programs under p4-samples are visible to other
@@ -27,5 +22,4 @@ exports_files(
         "**/*.txt",
     ]),
     licenses = ["notice"],
-    visibility = ["//p4_symbolic:__subpackages__"],
 )
diff --git a/p4_symbolic/tests/BUILD.bazel b/p4_symbolic/tests/BUILD.bazel
index 87daf147..013dcdcc 100644
--- a/p4_symbolic/tests/BUILD.bazel
+++ b/p4_symbolic/tests/BUILD.bazel
@@ -1,8 +1,3 @@
-load("@bazel_skylib//rules:build_test.bzl", "build_test")
-load("//p4_pdpi/testing:diff_test.bzl", "cmd_diff_test", "diff_test")
-load("//p4_pdpi:pdgen.bzl", "p4_pd_proto")
-load("@com_github_p4lang_p4c//:bazel/p4_library.bzl", "p4_library")
-
 package(
     default_visibility = ["//visibility:public"],
     licenses = ["notice"],
diff --git a/p4_symbolic/tests/sai_p4_component_test.cc b/p4_symbolic/tests/sai_p4_component_test.cc
index e6cbe62f..14944e0c 100644
--- a/p4_symbolic/tests/sai_p4_component_test.cc
+++ b/p4_symbolic/tests/sai_p4_component_test.cc
@@ -28,7 +28,7 @@ using ::p4::config::v1::P4Info;
 using ::testing::Eq;
 using ::testing::Not;
 
-constexpr absl::string_view kTableEntries = R"PB(
+constexpr absl::string_view kTableEntries = R"pb(
   entries {
     acl_pre_ingress_table_entry  {
       match {
@@ -73,7 +73,7 @@ constexpr absl::string_view kTableEntries = R"PB(
       action { set_dst_mac { dst_mac: "cc:bb:aa:99:88:77" } }
     }
   }
-)PB";
+)pb";
 
 class P4SymbolicComponentTest : public testing::Test {
  public:
diff --git a/p4_symbolic/util/BUILD.bazel b/p4_symbolic/util/BUILD.bazel
index b8070667..d9f9a016 100644
--- a/p4_symbolic/util/BUILD.bazel
+++ b/p4_symbolic/util/BUILD.bazel
@@ -12,11 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-load("@bazel_skylib//rules:build_test.bzl", "build_test")
-load("//p4_pdpi/testing:diff_test.bzl", "cmd_diff_test", "diff_test")
-load("//p4_pdpi:pdgen.bzl", "p4_pd_proto")
-load("@com_github_p4lang_p4c//:bazel/p4_library.bzl", "p4_library")
-
 package(
     default_visibility = ["//visibility:public"],
     licenses = ["notice"],
@@ -33,7 +28,6 @@ cc_library(
         # TODO: clean up.
         # "status.h",
     ],
-    visibility = ["//p4_symbolic:__subpackages__"],
     deps = [
         "//gutil:status",
         "@com_google_absl//absl/status",