Index: test/lit.cfg
===================================================================
--- test/lit.cfg
+++ test/lit.cfg
@@ -389,6 +389,9 @@
 # Sanitizers.
 if 'Address' in config.llvm_use_sanitizer:
     config.available_features.add("asan")
+    # LeakSanitizer is disabled by default on Darwin, enable it on 64-bit builds
+    if re.match(r'^x86_64-apple.*', config.target_triple):
+        config.environment['ASAN_OPTIONS'] = 'detect_leaks=1'
 else:
     config.available_features.add("not_asan")
 if 'Memory' in config.llvm_use_sanitizer:
Index: test/tools/lto/lit.local.cfg
===================================================================
--- test/tools/lto/lit.local.cfg
+++ test/tools/lto/lit.local.cfg
@@ -1,2 +1,6 @@
 if not ('ld64_plugin' in config.available_features and 'X86' in config.root.targets):
-   config.unsupported = True
+    config.unsupported = True
+
+# These tests invoke ld64 from the system, which is not leak-free
+if "Address" in config.llvm_use_sanitizer:
+    config.environment['ASAN_OPTIONS'] = 'detect_leaks=0'