diff --git a/openmp/runtime/CMakeLists.txt b/openmp/runtime/CMakeLists.txt
--- a/openmp/runtime/CMakeLists.txt
+++ b/openmp/runtime/CMakeLists.txt
@@ -34,6 +34,7 @@
   # Should assertions be enabled?  They are on by default.
   set(LIBOMP_ENABLE_ASSERTIONS TRUE CACHE BOOL
     "enable assertions?")
+  string(TOUPPER "${CMAKE_BUILD_TYPE}" uppercase_CMAKE_BUILD_TYPE)
 else() # Part of LLVM build
   # Determine the native architecture from LLVM.
   string(TOLOWER "${LLVM_TARGET_ARCH}" LIBOMP_NATIVE_ARCH)
@@ -189,14 +190,13 @@
 set(DEBUG_BUILD FALSE)
 set(RELWITHDEBINFO_BUILD FALSE)
 set(MINSIZEREL_BUILD FALSE)
-string(TOLOWER "${CMAKE_BUILD_TYPE}" libomp_build_type_lowercase)
-if("${libomp_build_type_lowercase}" STREQUAL "release")
+if("${uppercase_CMAKE_BUILD_TYPE}" STREQUAL "RELEASE")
   set(RELEASE_BUILD TRUE)
-elseif("${libomp_build_type_lowercase}" STREQUAL "debug")
+elseif("${uppercase_CMAKE_BUILD_TYPE}" STREQUAL "DEBUG")
   set(DEBUG_BUILD TRUE)
-elseif("${libomp_build_type_lowercase}" STREQUAL "relwithdebinfo")
+elseif("${uppercase_CMAKE_BUILD_TYPE}" STREQUAL "RELWITHDEBINFO")
   set(RELWITHDEBINFO_BUILD TRUE)
-elseif("${libomp_build_type_lowercase}" STREQUAL "minsizerel")
+elseif("${uppercase_CMAKE_BUILD_TYPE}" STREQUAL "MINSIZEREL")
   set(MINSIZEREL_BUILD TRUE)
 endif()