diff --git a/openmp/CMakeLists.txt b/openmp/CMakeLists.txt
index e7a26b13a67ff..94152f98d30f6 100644
--- a/openmp/CMakeLists.txt
+++ b/openmp/CMakeLists.txt
@@ -41,13 +41,26 @@ else()
       "Path where built OpenMP libraries should be installed.")
 endif()
 
-if (NOT MSVC)
-  set(OPENMP_TEST_C_COMPILER ${LLVM_TOOLS_BINARY_DIR}/clang)
-  set(OPENMP_TEST_CXX_COMPILER ${LLVM_TOOLS_BINARY_DIR}/clang++)
-else()
-  set(OPENMP_TEST_C_COMPILER ${LLVM_TOOLS_BINARY_DIR}/clang.exe)
-  set(OPENMP_TEST_CXX_COMPILER ${LLVM_TOOLS_BINARY_DIR}/clang++.exe)
+set(OPENMP_TEST_C_COMPILER_default "${LLVM_TOOLS_BINARY_DIR}/clang${CMAKE_EXECUTABLE_SUFFIX}")
+set(OPENMP_TEST_CXX_COMPILER_default "${LLVM_TOOLS_BINARY_DIR}/clang++${CMAKE_EXECUTABLE_SUFFIX}")
+set(OPENMP_TEST_Fortran_COMPILER_default "${LLVM_TOOLS_BINARY_DIR}/flang${CMAKE_EXECUTABLE_SUFFIX}")
+if (NOT TARGET "clang")
+  set(OPENMP_TEST_C_COMPILER_default "${CMAKE_C_COMPILER}")
+  set(OPENMP_TEST_CXX_COMPILER_default "${CMAKE_CXX_COMPILER}")
+endif()
+if (NOT TARGET "flang")
+  if (CMAKE_Fortran_COMPILER)
+    set(OPENMP_TEST_Fortran_COMPILER_default "${CMAKE_Fortran_COMPILER}")
+  else()
+    unset(OPENMP_TEST_Fortran_COMPILER_default)
+  endif()
 endif()
+set(OPENMP_TEST_C_COMPILER "${OPENMP_TEST_C_COMPILER_default}" CACHE STRING
+  "C compiler to use for testing OpenMP runtime libraries.")
+set(OPENMP_TEST_CXX_COMPILER "${OPENMP_TEST_CXX_COMPILER_default}" CACHE STRING
+  "C++ compiler to use for testing OpenMP runtime libraries.")
+set(OPENMP_TEST_Fortran_COMPILER "${OPENMP_TEST_Fortran_COMPILER_default}" CACHE STRING
+  "Fortran compiler to use for testing OpenMP runtime libraries.")
 
 # Set fortran test compiler if flang is found
 if (EXISTS "${OPENMP_TEST_Fortran_COMPILER}")
@@ -85,14 +98,6 @@ math(EXPR LIBOMP_VERSION_BUILD_MONTH_DAY "${LIBOMP_VERSION_BUILD}%10000")
 set(LIBOMP_BUILD_DATE "No_Timestamp")
 
 
-# Check for flang
-set(OPENMP_TEST_Fortran_COMPILER_default "")
-if (CMAKE_Fortran_COMPILER)
-  set(OPENMP_TEST_Fortran_COMPILER_default "${CMAKE_Fortran_COMPILER}")
-endif ()
-set(OPENMP_TEST_Fortran_COMPILER "${OPENMP_TEST_Fortran_COMPILER_default}" CACHE STRING
-  "Fortran compiler to use for testing OpenMP runtime libraries.")
-
 set(LIBOMP_FORTRAN_MODULES FALSE CACHE BOOL
   "Create Fortran module files? (requires fortran compiler)")
 
diff --git a/openmp/cmake/OpenMPTesting.cmake b/openmp/cmake/OpenMPTesting.cmake
index b1ee5bb664e1d..e6eb444c5f90f 100644
--- a/openmp/cmake/OpenMPTesting.cmake
+++ b/openmp/cmake/OpenMPTesting.cmake
@@ -127,19 +127,23 @@ function(add_openmp_testsuite target comment)
     set_property(GLOBAL APPEND PROPERTY OPENMP_LIT_DEPENDS ${ARG_DEPENDS})
   endif()
 
+  set(EXTRA_CHECK_DEPENDS "")
+  if (TARGET "clang")
+    list(APPEND EXTRA_CHECK_DEPENDS clang)
+  endif()
   if (ARG_EXCLUDE_FROM_CHECK_ALL)
     add_lit_testsuite(${target}
       ${comment}
       ${ARG_UNPARSED_ARGUMENTS}
       EXCLUDE_FROM_CHECK_ALL
-      DEPENDS clang FileCheck not ${ARG_DEPENDS}
+      DEPENDS ${EXTRA_CHECK_DEPENDS} FileCheck not ${ARG_DEPENDS}
       ARGS ${ARG_ARGS}
     )
   else()
     add_lit_testsuite(${target}
       ${comment}
       ${ARG_UNPARSED_ARGUMENTS}
-      DEPENDS clang FileCheck not ${ARG_DEPENDS}
+      DEPENDS ${EXTRA_CHECK_DEPENDS} FileCheck not ${ARG_DEPENDS}
       ARGS ${ARG_ARGS}
     )
   endif()
diff --git a/openmp/docs/Building.md b/openmp/docs/Building.md
index c023a6e6717df..460d4f03915f1 100644
--- a/openmp/docs/Building.md
+++ b/openmp/docs/Building.md
@@ -136,8 +136,8 @@ is expected to have been built from the same Git commit as OpenMP. It will,
 however, use the compiler detected by CMake, usually gcc.
 To also make it use Clang, add
 `-DCMAKE_C_COMPILER=../build/bin/clang -DCMAKE_C_COMPILER=../build/bin/clang++`.
-In any case, it will use Clang from `LLVM_BINARY_DIR` for running the regression
-tests. `LLVM_BINARY_DIR` can also be omitted in which case testing
+Clang/Flang from `LLVM_BINARY_DIR` will be used for testing if available, otherwise `CMAKE_C_COMPILER`/`CMAKE_CXX_COMPILER`/`CMAKE_Fortran_COMPILER`. Tests are also only expected to work with Clang/Flang built from the same Git commit, so `OPENMP_TEST_C_COMPILER`/`OPENMP_TEST_CXX_COMPILER`/`OPENMP_TEST_Fortran_COMPILER` can be used to explicitly set the test compilers.
+`LLVM_BINARY_DIR` can also be omitted in which case testing
 (`ninja check-openmp`) is disabled.
 
 The `CMAKE_INSTALL_PREFIX` can be the same, but does not need to. Using the same
@@ -269,6 +269,14 @@ tests.
 : Location, relative to [`CMAKE_INSTALL_PREFIX`][CMAKE_INSTALL_PREFIX], where to
 install the OpenMP libraries (`.a` and `.so`)
 
+**OPENMP_TEST_C_COMPILER**:STRING (default: Clang built in the same build configuration, or **CMAKE_C_COMPILER**)
+: C compiler to use for testing OpenMP runtime libraries.
+
+**OPENMP_TEST_CXX_COMPILER**:STRING (default: Clang built in the same build configuration, or **CMAKE_CXX_COMPILER**)
+: C++ compiler to use for testing OpenMP runtime libraries.
+
+**OPENMP_TEST_Fortran_COMPILER**:STRING (default: Flang built in the same build configuration, or **CMAKE_Fortran_COMPILER**)
+: Fortran compiler to use for testing OpenMP runtime libraries.
 
 ### Options for `libomp`