diff --git a/garnet/bin/cpuperf_provider/BUILD.gn b/garnet/bin/cpuperf_provider/BUILD.gn
index 28ea888..5c1c089 100644
--- a/garnet/bin/cpuperf_provider/BUILD.gn
+++ b/garnet/bin/cpuperf_provider/BUILD.gn
@@ -111,8 +111,8 @@
       "//src/lib/fxl",
       "//src/lib/fxl/test:test_settings",
       "//third_party/googletest:gtest",
-      "//zircon/public/lib/trace-reader",
       "//zircon/public/lib/zx",
+      "//zircon/system/ulib/trace-reader",
     ]
   }
 }
diff --git a/garnet/bin/trace/BUILD.gn b/garnet/bin/trace/BUILD.gn
index 95b4cf3..fd16091 100644
--- a/garnet/bin/trace/BUILD.gn
+++ b/garnet/bin/trace/BUILD.gn
@@ -51,7 +51,7 @@
     "//zircon/public/lib/async-loop-default",
     "//zircon/public/lib/fdio",
     "//zircon/public/lib/fit",
-    "//zircon/public/lib/trace-reader",
+    "//zircon/system/ulib/trace-reader",
   ]
 
   deps = [
diff --git a/garnet/bin/trace/tests/BUILD.gn b/garnet/bin/trace/tests/BUILD.gn
index 84cee2d..10a524f 100644
--- a/garnet/bin/trace/tests/BUILD.gn
+++ b/garnet/bin/trace/tests/BUILD.gn
@@ -124,7 +124,7 @@
     "//zircon/public/lib/async-cpp",
     "//zircon/public/lib/fdio",
     "//zircon/public/lib/trace",
-    "//zircon/public/lib/trace-reader",
+    "//zircon/system/ulib/trace-reader",
   ]
 }
 
@@ -152,8 +152,8 @@
     "//third_party/rapidjson",
     "//zircon/public/lib/async-cpp",
     "//zircon/public/lib/fdio",
-    "//zircon/public/lib/trace-reader",
     "//zircon/public/lib/trace-with-static-engine",
+    "//zircon/system/ulib/trace-reader",
   ]
 }
 
@@ -354,8 +354,8 @@
     ":run_test",
     "//src/developer/tracing/lib/test_utils",
     "//third_party/googletest:gtest",
-    "//zircon/public/lib/trace-reader",
     "//zircon/public/lib/zx",
+    "//zircon/system/ulib/trace-reader",
   ]
 }
 
@@ -385,8 +385,8 @@
     ":integration_test_utils",
     ":run_test",
     "//third_party/googletest:gtest",
-    "//zircon/public/lib/trace-reader",
     "//zircon/public/lib/zx",
+    "//zircon/system/ulib/trace-reader",
   ]
 }
 
@@ -416,8 +416,8 @@
     ":integration_test_utils",
     ":run_test",
     "//third_party/googletest:gtest",
-    "//zircon/public/lib/trace-reader",
     "//zircon/public/lib/zx",
+    "//zircon/system/ulib/trace-reader",
   ]
 }
 
diff --git a/garnet/bin/trace2json/BUILD.gn b/garnet/bin/trace2json/BUILD.gn
index af342da..3d90f36 100644
--- a/garnet/bin/trace2json/BUILD.gn
+++ b/garnet/bin/trace2json/BUILD.gn
@@ -31,7 +31,7 @@
     "//garnet/lib/trace_converters:chromium",
     "//third_party/rapidjson",
     "//third_party/zlib:zfstream",
-    "//zircon/public/lib/trace-reader",
+    "//zircon/system/ulib/trace-reader",
   ]
 }
 
diff --git a/garnet/bin/trace_manager/BUILD.gn b/garnet/bin/trace_manager/BUILD.gn
index b5d289b..7ac02999 100644
--- a/garnet/bin/trace_manager/BUILD.gn
+++ b/garnet/bin/trace_manager/BUILD.gn
@@ -36,9 +36,9 @@
     "//src/lib/fxl",
     "//zircon/public/lib/async-cpp",
     "//zircon/public/lib/fit",
-    "//zircon/public/lib/trace-reader",
     "//zircon/public/lib/zx",
     "//zircon/system/fidl/fuchsia-tracing-provider",
+    "//zircon/system/ulib/trace-reader",
   ]
 }
 
diff --git a/garnet/lib/measure/BUILD.gn b/garnet/lib/measure/BUILD.gn
index 50cd65a..a551e36 100644
--- a/garnet/lib/measure/BUILD.gn
+++ b/garnet/lib/measure/BUILD.gn
@@ -19,7 +19,7 @@
 
   public_deps = [
     "//src/lib/fxl",
-    "//zircon/public/lib/trace-reader",
+    "//zircon/system/ulib/trace-reader",
   ]
 }
 
diff --git a/garnet/lib/trace_converters/BUILD.gn b/garnet/lib/trace_converters/BUILD.gn
index 0544685..438f9e6 100644
--- a/garnet/lib/trace_converters/BUILD.gn
+++ b/garnet/lib/trace_converters/BUILD.gn
@@ -21,7 +21,7 @@
   public_deps = [
     "//garnet/lib/perfmon",
     "//third_party/rapidjson",
-    "//zircon/public/lib/trace-reader",
+    "//zircon/system/ulib/trace-reader",
   ]
 }
 
diff --git a/zircon/system/ulib/BUILD.gn b/zircon/system/ulib/BUILD.gn
index d7432a7..a0d5ef6 100644
--- a/zircon/system/ulib/BUILD.gn
+++ b/zircon/system/ulib/BUILD.gn
@@ -493,7 +493,6 @@
     "trace-provider:trace-provider-with-static-engine",
 #------------------
 #------------------
-    "trace-reader",
 #------------------
 #------------------
 #------------------
@@ -680,7 +679,6 @@
     "trace-engine:trace-engine-headers-for-reader",
 #------------------
 #------------------
-    "trace-reader",
 #------------------
 #------------------
     "unittest:unittest-static",
diff --git a/zircon/system/ulib/trace-reader/BUILD.gn b/zircon/system/ulib/trace-reader/BUILD.gn
index df8d8c2..1b6eee9 100644
--- a/zircon/system/ulib/trace-reader/BUILD.gn
+++ b/zircon/system/ulib/trace-reader/BUILD.gn
@@ -2,6 +2,18 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+##########################################
+# Though under //zircon, this build file #
+# is meant to be used in the Fuchsia GN  #
+# build.                                 #
+# See fxb/36548.                         #
+##########################################
+
+assert(!defined(zx) || zx != "/",
+       "This file can only be used in the Fuchsia GN build.")
+
+import("//build/unification/zx_library.gni")
+
 zx_library("trace-reader") {
   sdk = "source"
   sdk_headers = [
@@ -19,21 +31,21 @@
   ]
   public_deps = [
     # <trace-reader/records.h> has #include <trace-engine/types.h>.
-    "$zx/system/ulib/trace-engine:trace-engine-headers-for-reader.headers",
+    "//zircon/public/lib/trace-engine-headers-for-reader",
 
     # <trace-reader/records.h> has #include <fbl/array.h>.
-    "$zx/system/ulib/fbl:headers",
+    "//zircon/public/lib/fbl",
 
     # <trace-reader/records.h> has #include <lib/fit/variant.h>.
-    "$zx/system/ulib/fit:headers",
+    "//zircon/public/lib/fit",
   ]
   deps = [
-    "$zx/system/ulib/fbl",
-    "$zx/system/ulib/fit",
+    "//zircon/public/lib/fbl",
+    "//zircon/public/lib/fit",
   ]
 
   # TODO(41892): UBSan has found an instance of undefined behavior in this target.
   # Disable UBSan for this target temporarily until it is migrated into CI/CQ.
   configs +=
-      [ "$zx_build/public/gn/config:temporarily_disable_ubsan_do_not_use" ]
+      [ "//build/config:temporarily_disable_ubsan_do_not_use" ]
 }
diff --git a/zircon/system/ulib/trace-reader/test/BUILD.gn b/zircon/system/ulib/trace-reader/test/BUILD.gn
index b9a0aaf..1deb9cb 100644
--- a/zircon/system/ulib/trace-reader/test/BUILD.gn
+++ b/zircon/system/ulib/trace-reader/test/BUILD.gn
@@ -34,8 +34,8 @@
     "//zircon/public/lib/fbl",
     "//zircon/public/lib/fit",
     "//zircon/public/lib/trace-engine-headers-for-reader",
-    "//zircon/public/lib/trace-reader",
     "//zircon/public/lib/zxtest",
+    "//zircon/system/ulib/trace-reader",
   ]
   if (is_fuchsia) {
     deps += [
diff --git a/zircon/system/ulib/trace-test-utils/BUILD.gn b/zircon/system/ulib/trace-test-utils/BUILD.gn
index 5d5a665..278b195 100644
--- a/zircon/system/ulib/trace-test-utils/BUILD.gn
+++ b/zircon/system/ulib/trace-test-utils/BUILD.gn
@@ -36,7 +36,7 @@
     "//zircon/public/lib/async-loop",
     "//zircon/public/lib/fbl",
     "//zircon/public/lib/trace-engine",
-    "//zircon/public/lib/trace-reader",
+    "//zircon/system/ulib/trace-reader",
   ]
   deps = [
     # The kind of engine to use is up to the client, so we don't provide any
@@ -46,7 +46,7 @@
     "//zircon/public/lib/async-loop-default",
     "//zircon/public/lib/fbl",
     "//zircon/public/lib/trace-handler",
-    "//zircon/public/lib/trace-reader",
     "//zircon/public/lib/zx",
+    "//zircon/system/ulib/trace-reader",
   ]
 }
diff --git a/zircon/system/ulib/trace-vthread/test/BUILD.gn b/zircon/system/ulib/trace-vthread/test/BUILD.gn
index 32e7d44..321c591 100644
--- a/zircon/system/ulib/trace-vthread/test/BUILD.gn
+++ b/zircon/system/ulib/trace-vthread/test/BUILD.gn
@@ -38,10 +38,10 @@
     "//zircon/public/lib/fdio",
     "//zircon/public/lib/trace",
     "//zircon/public/lib/trace-handler",
-    "//zircon/public/lib/trace-reader",
     "//zircon/public/lib/trace-vthread",
     "//zircon/public/lib/unittest",
     "//zircon/public/lib/zx",
+    "//zircon/system/ulib/trace-reader",
     "//zircon/system/ulib/trace-test-utils",
   ]
 }
diff --git a/zircon/system/utest/trace/BUILD.gn b/zircon/system/utest/trace/BUILD.gn
index 4f390eb..061cc58 100644
--- a/zircon/system/utest/trace/BUILD.gn
+++ b/zircon/system/utest/trace/BUILD.gn
@@ -40,9 +40,9 @@
 
     # The engine is chosen by the binary, we just need engine headers here.
     "//zircon/public/lib/trace-engine-headers-for-reader",
-    "//zircon/public/lib/trace-reader",
     "//zircon/public/lib/unittest",
     "//zircon/public/lib/zx",
+    "//zircon/system/ulib/trace-reader",
     "//zircon/system/ulib/trace-test-utils",
 
     # fdio is here so that things like printf work.