diff --git a/llvm/CMakeLists.txt b/llvm/CMakeLists.txt
--- a/llvm/CMakeLists.txt
+++ b/llvm/CMakeLists.txt
@@ -105,6 +105,20 @@
 ")
 endif()
 
+# Set default build type for cmake's try_compile module.
+# CMake 3.17 or newer sets CMAKE_DEFAULT_BUILD_TYPE to one of the
+# items from CMAKE_CONFIGURATION_TYPES. Logic below can be further
+# simplified once LLVM's minimum CMake version is updated to 3.17.
+if(CMAKE_DEFAULT_BUILD_TYPE)
+  set(CMAKE_TRY_COMPILE_CONFIGURATION ${CMAKE_DEFAULT_BUILD_TYPE})
+else()
+  if(CMAKE_CONFIGURATION_TYPES)
+    list(GET CMAKE_CONFIGURATION_TYPES 0 CMAKE_TRY_COMPILE_CONFIGURATION)
+  elseif(CMAKE_BUILD_TYPE)
+    set(CMAKE_TRY_COMPILE_CONFIGURATION ${CMAKE_BUILD_TYPE})
+  endif()
+endif()
+
 # Side-by-side subprojects layout: automatically set the
 # LLVM_EXTERNAL_${project}_SOURCE_DIR using LLVM_ALL_PROJECTS
 # This allows an easy way of setting up a build directory for llvm and another