diff --git a/lldb/packages/Python/lldbsuite/test/lldbplatformutil.py b/lldb/packages/Python/lldbsuite/test/lldbplatformutil.py
index 21f2095db90f8..818fdf0e6b5c5 100644
--- a/lldb/packages/Python/lldbsuite/test/lldbplatformutil.py
+++ b/lldb/packages/Python/lldbsuite/test/lldbplatformutil.py
@@ -92,11 +92,28 @@ def match_android_device(device_arch, valid_archs=None, valid_api_levels=None):
 
 
 def finalize_build_dictionary(dictionary):
+    # Provide uname-like platform name
+    platform_name_to_uname = {
+        "linux": "Linux",
+        "netbsd": "NetBSD",
+        "freebsd": "FreeBSD",
+        "windows": "Windows_NT",
+        "macosx": "Darwin",
+        "darwin": "Darwin",
+    }
+
+    if dictionary is None:
+        dictionary = {}
     if target_is_android():
-        if dictionary is None:
-            dictionary = {}
         dictionary["OS"] = "Android"
         dictionary["PIE"] = 1
+    elif platformIsDarwin():
+        dictionary["OS"] = "Darwin"
+    else:
+        dictionary["OS"] = platform_name_to_uname[getPlatform()]
+
+    dictionary["HOST_OS"] = platform_name_to_uname[getHostPlatform()]
+
     return dictionary
 
 
diff --git a/lldb/packages/Python/lldbsuite/test/make/Makefile.rules b/lldb/packages/Python/lldbsuite/test/make/Makefile.rules
index bd8eea3d6f5a0..3d562285ce9cc 100644
--- a/lldb/packages/Python/lldbsuite/test/make/Makefile.rules
+++ b/lldb/packages/Python/lldbsuite/test/make/Makefile.rules
@@ -55,7 +55,10 @@ LLDB_BASE_DIR := $(THIS_FILE_DIR)/../../../../../
 # When running tests from Visual Studio, the environment variable isn't
 # inherited all the way down to the process spawned for make.
 #----------------------------------------------------------------------
-HOST_OS := $(shell uname -s)
+ifeq "$(HOST_OS)" ""
+  HOST_OS := $(shell uname -s)
+endif
+
 ifneq (,$(findstring windows32,$(HOST_OS)))
 	HOST_OS := Windows_NT
 endif