diff --git a/runtimes/CMakeLists.txt b/runtimes/CMakeLists.txt
--- a/runtimes/CMakeLists.txt
+++ b/runtimes/CMakeLists.txt
@@ -111,9 +111,13 @@
 
 find_package(Python3 REQUIRED COMPONENTS Interpreter)
 
+# Host triple is used by tests to check if they are running natively.
+include(GetHostTriple)
 if (NOT LLVM_DEFAULT_TARGET_TRIPLE)
-  include(GetHostTriple)
   get_host_triple(LLVM_DEFAULT_TARGET_TRIPLE)
+  set(LLVM_HOST_TRIPLE ${LLVM_DEFAULT_TARGET_TRIPLE})
+else()
+  get_host_triple(LLVM_HOST_TRIPLE)
 endif()
 
 option(LLVM_INCLUDE_TESTS "Generate build targets for the runtimes unit tests." ON)