Index: lldb/CMakeLists.txt
===================================================================
--- lldb/CMakeLists.txt
+++ lldb/CMakeLists.txt
@@ -70,8 +70,6 @@
 add_subdirectory(docs)
 
 option(LLDB_INCLUDE_TESTS "Generate build targets for the LLDB unit tests." ${LLVM_INCLUDE_TESTS})
-option(LLDB_TEST_USE_CUSTOM_C_COMPILER "Use the C compiler provided via LLDB_TEST_C_COMPILER for building test inferiors (instead of the just-built compiler). Defaults to OFF." OFF)
-option(LLDB_TEST_USE_CUSTOM_CXX_COMPILER "Use the C++ compiler provided via LLDB_TEST_CXX_COMPILER for building test inferiors (instead of the just-built compiler). Defaults to OFF." OFF)
 if(LLDB_INCLUDE_TESTS)
 
   # Set the path to the default lldb test executable.
@@ -81,27 +79,33 @@
   set(LLDB_DEFAULT_TEST_DSYMUTIL "${LLVM_BINARY_DIR}/${CMAKE_CFG_INTDIR}/bin/dsymutil${CMAKE_EXECUTABLE_SUFFIX}")
   set(LLDB_DEFAULT_TEST_FILECHECK "${LLVM_BINARY_DIR}/${CMAKE_CFG_INTDIR}/bin/FileCheck${CMAKE_EXECUTABLE_SUFFIX}")
 
-  if (NOT LLDB_TEST_USE_CUSTOM_C_COMPILER AND TARGET clang)
+  if (TARGET clang)
     set(LLDB_DEFAULT_TEST_C_COMPILER "${LLVM_BINARY_DIR}/${CMAKE_CFG_INTDIR}/bin/clang${CMAKE_EXECUTABLE_SUFFIX}")
+    set(LLDB_DEFAULT_TEST_CXX_COMPILER "${LLVM_BINARY_DIR}/${CMAKE_CFG_INTDIR}/bin/clang++${CMAKE_EXECUTABLE_SUFFIX}")
   else()
     set(LLDB_DEFAULT_TEST_C_COMPILER "")
+    set(LLDB_DEFAULT_TEST_CXX_COMPILER "")
   endif()
 
-  if (NOT LLDB_TEST_USE_CUSTOM_CXX_COMPILER AND TARGET clang)
-    set(LLDB_DEFAULT_TEST_CXX_COMPILER "${LLVM_BINARY_DIR}/${CMAKE_CFG_INTDIR}/bin/clang++${CMAKE_EXECUTABLE_SUFFIX}")
-  else()
-    set(LLDB_DEFAULT_TEST_CXX_COMPILER "")
+  # Use the default C compiler if LLDB_TEST_C_COMPILER is explicitly unset.
+  if (LLDB_TEST_C_COMPILER STREQUAL "")
+    set(LLDB_TEST_C_COMPILER_force FORCE)
+  endif()
+
+  # Use the default C++ compiler if LLDB_TEST_CXX_COMPILER is explicitly unset.
+  if (LLDB_TEST_CXX_COMPILER STREQUAL "")
+    set(LLDB_TEST_CXX_COMPILER_force FORCE)
   endif()
 
   set(LLDB_TEST_EXECUTABLE "${LLDB_DEFAULT_TEST_EXECUTABLE}" CACHE PATH "lldb executable used for testing")
-  set(LLDB_TEST_C_COMPILER "${LLDB_DEFAULT_TEST_C_COMPILER}" CACHE PATH "C Compiler to use for building LLDB test inferiors")
-  set(LLDB_TEST_CXX_COMPILER "${LLDB_DEFAULT_TEST_CXX_COMPILER}" CACHE PATH "C++ Compiler to use for building LLDB test inferiors")
+  set(LLDB_TEST_C_COMPILER "${LLDB_DEFAULT_TEST_C_COMPILER}" CACHE PATH "C Compiler to use for building LLDB test inferiors" ${LLDB_TEST_C_COMPILER_force})
+  set(LLDB_TEST_CXX_COMPILER "${LLDB_DEFAULT_TEST_CXX_COMPILER}" CACHE PATH "C++ Compiler to use for building LLDB test inferiors" ${LLDB_TEST_CXX_COMPILER_force})
   set(LLDB_TEST_DSYMUTIL "${LLDB_DEFAULT_TEST_DSYMUTIL}" CACHE PATH "dsymutil used for generating dSYM bundles")
   set(LLDB_TEST_FILECHECK "${LLDB_DEFAULT_TEST_FILECHECK}" CACHE PATH "FileCheck used for testing purposes")
 
   if (("${LLDB_TEST_C_COMPILER}" STREQUAL "") OR
       ("${LLDB_TEST_CXX_COMPILER}" STREQUAL ""))
-    message(FATAL_ERROR "LLDB test compilers not specified.  Tests will not run")
+    message(FATAL_ERROR "LLDB test compilers not specified. Tests will not run.")
   endif()
 
   set(LLDB_TEST_DEPS lldb)
Index: lldb/docs/resources/build.rst
===================================================================
--- lldb/docs/resources/build.rst
+++ lldb/docs/resources/build.rst
@@ -185,8 +185,6 @@
 ::
 
   > cmake -G Ninja \
-      -DLLDB_TEST_USE_CUSTOM_C_COMPILER=On \
-      -DLLDB_TEST_USE_CUSTOM_CXX_COMPILER=On \
       -DLLDB_TEST_C_COMPILER=<path to C compiler> \
       -DLLDB_TEST_CXX_COMPILER=<path to C++ compiler> \
       <path to root of llvm source tree>
@@ -228,7 +226,6 @@
   > cmake -G Ninja^
       -DLLDB_TEST_DEBUG_TEST_CRASHES=1^
       -DPYTHON_HOME=C:\Python35^
-      -DLLDB_TEST_USE_CUSTOM_C_COMPILER=ON^
       -DLLDB_TEST_C_COMPILER=d:\src\llvmbuild\ninja_release\bin\clang.exe^
       <path to root of llvm source tree>
 
Index: lldb/docs/resources/test.rst
===================================================================
--- lldb/docs/resources/test.rst
+++ lldb/docs/resources/test.rst
@@ -30,9 +30,7 @@
 By default, the ``check-lldb`` target builds the test programs with the same
 compiler that was used to build LLDB. To build the tests with a different
 compiler, you can set the ``LLDB_TEST_C_COMPILER`` or the
-``LLDB_TEST_CXX_COMPILER`` CMake variables. These variables are ignored unless
-the respective ``LLDB_TEST_USE_CUSTOM_C_COMPILER`` and
-``LLDB_TEST_USE_CUSTOM_CXX_COMPILER`` are set to ``ON``.
+``LLDB_TEST_CXX_COMPILER`` CMake variables.
 
 It is possible to customize the architecture of the test binaries and compiler
 used by appending ``-A`` and ``-C`` options respectively to the CMake variable