diff --git a/Package.swift b/Package.swift
index 840541887..e387f1453 100644
--- a/Package.swift
+++ b/Package.swift
@@ -470,12 +470,6 @@ extension Array where Element == PackageDescription.CXXSetting {
 
     // Capture the testing library's commit info as C++ constants.
     if let git {
-      if let tag = git.currentTag {
-        result.append(.define("SWT_TESTING_LIBRARY_VERSION", to: #""\#(tag)""#))
-      } else {
-        result.append(.define("SWT_TESTING_LIBRARY_VERSION", to: "0"))
-      }
-
       result.append(.define("SWT_TESTING_LIBRARY_COMMIT_HASH", to: #""\#(git.currentCommit)""#))
       if git.hasUncommittedChanges {
         result.append(.define("SWT_TESTING_LIBRARY_COMMIT_MODIFIED", to: "1"))
@@ -483,7 +477,6 @@ extension Array where Element == PackageDescription.CXXSetting {
     } else if let gitHubSHA = Context.environment["GITHUB_SHA"] {
       // When building in GitHub Actions, the git command may fail to get us the
       // commit hash, so check if GitHub shared it with us instead.
-      result.append(.define("SWT_TESTING_LIBRARY_VERSION", to: "0"))
       result.append(.define("SWT_TESTING_LIBRARY_COMMIT_HASH", to: #""\#(gitHubSHA)""#))
     }
 
diff --git a/Sources/_TestingInternals/CMakeLists.txt b/Sources/_TestingInternals/CMakeLists.txt
index 90ad424e9..a951c7d4b 100644
--- a/Sources/_TestingInternals/CMakeLists.txt
+++ b/Sources/_TestingInternals/CMakeLists.txt
@@ -9,7 +9,6 @@
 set(CMAKE_CXX_SCAN_FOR_MODULES 0)
 
 include(GitCommit)
-include(LibraryVersion)
 include(TargetTriple)
 add_library(_TestingInternals STATIC
   Discovery.cpp
diff --git a/Sources/_TestingInternals/Versions.cpp b/Sources/_TestingInternals/Versions.cpp
index 8e85f3d06..bd8f2314a 100644
--- a/Sources/_TestingInternals/Versions.cpp
+++ b/Sources/_TestingInternals/Versions.cpp
@@ -10,11 +10,37 @@
 
 #include "Versions.h"
 
+#include <array>
+#include <algorithm>
+#include <iterator>
+
 const char *swt_getTestingLibraryVersion(void) {
 #if defined(SWT_TESTING_LIBRARY_VERSION)
+  // The current environment explicitly specifies a version string to return.
   return SWT_TESTING_LIBRARY_VERSION;
+#elif __has_embed("../../VERSION.txt")
+  static constinit auto version = [] () constexpr {
+    // Read the version from version.txt at the root of the package's repo.
+    char version[] = {
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wc23-extensions"
+#embed "../../VERSION.txt"
+#pragma clang diagnostic pop
+    };
+
+    // Copy the first line from the C string into a C array so that we can
+    // return it from this closure.
+    std::array<char, std::size(version) + 1> result {};
+    auto i = std::find_if(std::begin(version), std::end(version), [] (char c) {
+      return c == '\r' || c == '\n';
+    });
+    std::copy(std::begin(version), i, result.begin());
+    return result;
+  }();
+
+  return version.data();
 #else
-#warning SWT_TESTING_LIBRARY_VERSION not defined: testing library version is unavailable
+#warning SWT_TESTING_LIBRARY_VERSION not defined and VERSION.txt not found: testing library version is unavailable
   return nullptr;
 #endif
 }
diff --git a/VERSION.txt b/VERSION.txt
new file mode 100644
index 000000000..a2b88412f
--- /dev/null
+++ b/VERSION.txt
@@ -0,0 +1 @@
+6.3-dev
diff --git a/cmake/modules/LibraryVersion.cmake b/cmake/modules/LibraryVersion.cmake
index 72e42e4cb..c5c1d6405 100644
--- a/cmake/modules/LibraryVersion.cmake
+++ b/cmake/modules/LibraryVersion.cmake
@@ -1,17 +1,12 @@
 ##
 ## This source file is part of the Swift.org open source project
 ##
-## Copyright (c) 2024 Apple Inc. and the Swift project authors
+## Copyright (c) 2024–2025 Apple Inc. and the Swift project authors
 ## Licensed under Apache License v2.0 with Runtime Library Exception
 ##
 ## See https://swift.org/LICENSE.txt for license information
 ## See https://swift.org/CONTRIBUTORS.txt for Swift project authors
 ##
 
-# The current version of the Swift Testing release. For release branches,
-# remember to remove -dev.
-set(SWT_TESTING_LIBRARY_VERSION "6.3-dev")
-
-message(STATUS "Swift Testing version: ${SWT_TESTING_LIBRARY_VERSION}")
-add_compile_definitions(
-  "$<$<COMPILE_LANGUAGE:CXX>:SWT_TESTING_LIBRARY_VERSION=\"${SWT_TESTING_LIBRARY_VERSION}\">")
+# The library version is now tracked in VERSION.txt at the root directory of the
+# repository. This file will be removed in a future commit.