diff --git a/pkgs/development/tools/build-managers/bear/default.nix b/pkgs/development/tools/build-managers/bear/default.nix
index 880184880db11ab..2789d3cefaffe71 100644
--- a/pkgs/development/tools/build-managers/bear/default.nix
+++ b/pkgs/development/tools/build-managers/bear/default.nix
@@ -2,6 +2,7 @@
 , fetchFromGitHub
 , fetchpatch
 , cmake
+, ninja
 , pkg-config
 , grpc
 , protobuf
@@ -13,6 +14,9 @@
 , zlib
 , sqlite
 , re2
+, lit
+, python3
+, coreutils
 }:
 
 stdenv.mkDerivation rec {
@@ -26,7 +30,15 @@ stdenv.mkDerivation rec {
     hash = "sha256-1nZPzgLWcmaRkOUXdm16IW2Nw/p1w8GBGEfZX/v+En0=";
   };
 
-  nativeBuildInputs = [ cmake pkg-config ];
+  nativeBuildInputs = [
+    cmake
+    ninja
+    pkg-config
+
+    # Used for functional tests, which run during buildPhase.
+    lit
+    python3
+  ];
 
   buildInputs = [
     grpc
@@ -41,13 +53,32 @@ stdenv.mkDerivation rec {
     re2
   ];
 
+  cmakeFlags = [
+    # Build system and generated files concatenate install prefix and
+    # CMAKE_INSTALL_{BIN,LIB}DIR, which breaks if these are absolute paths.
+    "-DCMAKE_INSTALL_BINDIR=bin"
+    "-DCMAKE_INSTALL_LIBDIR=lib"
+    (lib.cmakeBool "ENABLE_UNIT_TESTS" false)
+    (lib.cmakeBool "ENABLE_FUNC_TESTS" false)
+  ];
+
   patches = [
-    # Default libexec would be set to /nix/store/*-bear//nix/store/*-bear/libexec/...
-    ./no-double-relative.patch
+    # Fix toolchain environment variable handling and the Darwin SIP check.
+    ./fix-functional-tests.patch
   ];
 
+  postPatch = ''
+    patchShebangs test/bin
+
+    # /usr/bin/env is used in test commands and embedded scripts.
+    find test -name '*.sh' \
+      -exec sed -ie 's|/usr/bin/env|${coreutils}/bin/env|g' {} +
+  '';
+
+  # Functional tests use loopback networking.
+  __darwinAllowLocalNetworking = true;
+
   meta = with lib; {
-    broken = stdenv.isDarwin;
     description = "Tool that generates a compilation database for clang tooling";
     longDescription = ''
       Note: the bear command is very useful to generate compilation commands
diff --git a/pkgs/development/tools/build-managers/bear/fix-functional-tests.patch b/pkgs/development/tools/build-managers/bear/fix-functional-tests.patch
new file mode 100644
index 000000000000000..99d64f26d077ebf
--- /dev/null
+++ b/pkgs/development/tools/build-managers/bear/fix-functional-tests.patch
@@ -0,0 +1,32 @@
+diff --git a/test/lit.cfg b/test/lit.cfg
+index 118c979..b69fecc 100644
+--- a/test/lit.cfg
++++ b/test/lit.cfg
+@@ -207,13 +207,8 @@ def is_preload_disabled():
+     if is_windows:
+         return True
+     elif sys.platform == 'darwin':
+-        command = ['csrutil', 'status']
+-        pattern = re.compile(r'System Integrity Protection status:\s+enabled')
+-        try:
+-            output = subprocess.check_output(command, stderr=subprocess.STDOUT)
+-            return any(pattern.match(line) for line in output.decode('utf-8').splitlines())
+-        except (OSError, subprocess.CalledProcessError):
+-            return False
++        # csrutil(8) isn't available in the Nix build sandbox.
++        return True
+     else:
+         return False
+ 
+@@ -221,6 +216,11 @@ def is_preload_disabled():
+ if not is_preload_disabled():
+     config.available_features.add('preload')
+ 
++# Preserve the variables required for the Nix toolchain wrappers.
++for var, value in os.environ.items():
++    if var.startswith('NIX_'):
++        config.environment[var] = value
++
+ print(config.substitutions)
+ print(config.environment)
+ print(config.available_features)
diff --git a/pkgs/development/tools/build-managers/bear/no-double-relative.patch b/pkgs/development/tools/build-managers/bear/no-double-relative.patch
deleted file mode 100644
index e8087feb1afb2b8..000000000000000
--- a/pkgs/development/tools/build-managers/bear/no-double-relative.patch
+++ /dev/null
@@ -1,27 +0,0 @@
-diff --git a/source/config.h.in b/source/config.h.in
-index 6b659c2..f7bdf22 100644
---- a/source/config.h.in
-+++ b/source/config.h.in
-@@ -108,8 +108,8 @@ namespace cmd {
-     }
- 
-     namespace wrapper {
--        constexpr char DEFAULT_PATH[] = "@ROOT_INSTALL_PREFIX@/@CMAKE_INSTALL_LIBDIR@/bear/wrapper";
--        constexpr char DEFAULT_DIR_PATH[] = "@ROOT_INSTALL_PREFIX@/@CMAKE_INSTALL_LIBDIR@/bear/wrapper.d";
-+        constexpr char DEFAULT_PATH[] = "@CMAKE_INSTALL_LIBDIR@/bear/wrapper";
-+        constexpr char DEFAULT_DIR_PATH[] = "@CMAKE_INSTALL_LIBDIR@/bear/wrapper.d";
- 
-         constexpr char FLAG_VERBOSE[] = "--verbose";
-         constexpr char FLAG_DESTINATION[] = "--destination";
-@@ -134,9 +134,9 @@ namespace cmd {
-         // And use the `libexec.so` path default value with a single path,
-         // that matches both. (The match can be achieved by the $LIB token
-         // expansion from the dynamic loader. See `man ld.so` for more.)
--        constexpr char DEFAULT_PATH[] = "@ROOT_INSTALL_PREFIX@/$LIB/bear/@CMAKE_SHARED_LIBRARY_PREFIX@exec@CMAKE_SHARED_LIBRARY_SUFFIX@";
-+        constexpr char DEFAULT_PATH[] = "$LIB/bear/@CMAKE_SHARED_LIBRARY_PREFIX@exec@CMAKE_SHARED_LIBRARY_SUFFIX@";
- #else
--        constexpr char DEFAULT_PATH[] = "@ROOT_INSTALL_PREFIX@/@CMAKE_INSTALL_LIBDIR@/bear/@CMAKE_SHARED_LIBRARY_PREFIX@exec@CMAKE_SHARED_LIBRARY_SUFFIX@";
-+        constexpr char DEFAULT_PATH[] = "@CMAKE_INSTALL_LIBDIR@/bear/@CMAKE_SHARED_LIBRARY_PREFIX@exec@CMAKE_SHARED_LIBRARY_SUFFIX@";
- #endif
-         constexpr char KEY_REPORTER[] = "INTERCEPT_REPORT_COMMAND";
-         constexpr char KEY_DESTINATION[] = "INTERCEPT_REPORT_DESTINATION";