Index: test/builtins/CMakeLists.txt
===================================================================
--- test/builtins/CMakeLists.txt
+++ test/builtins/CMakeLists.txt
@@ -44,6 +44,33 @@
     string(REPLACE ";" " " BUILTINS_TEST_TARGET_CFLAGS "${BUILTINS_TEST_TARGET_CFLAGS}")
   endif()
 
+  # Compute builtins available in library and add them as lit features.
+  if(APPLE)
+    # TODO: Support other Apple platforms.
+    set(BUILTIN_LIB_TARGET_NAME "clang_rt.builtins_${arch}_osx")
+  else()
+    set(BUILTIN_LIB_TARGET_NAME "clang_rt.builtins-${arch}")
+  endif()
+  if (NOT TARGET "${BUILTIN_LIB_TARGET_NAME}")
+    message(FATAL_ERROR "Target ${BUILTIN_LIB_TARGET_NAME} does not exist")
+  endif()
+  get_target_property(BUILTIN_LIB_SOURCES "${BUILTIN_LIB_TARGET_NAME}" SOURCES)
+  list(LENGTH BUILTIN_LIB_SOURCES BUILTIN_LIB_SOURCES_LENGTH)
+  if (BUILTIN_LIB_SOURCES_LENGTH EQUAL 0)
+    message(FATAL_ERROR "Failed to find source files for ${arch} builtin library")
+  endif()
+  set(BUILTINS_LIT_SOURCE_FEATURES "")
+  foreach (file_name ${BUILTIN_LIB_SOURCES})
+    # Strip off any directories and file extensions. This approach means we add
+    # add a single feature if there is a C source file or assembly override
+    # present in the builtin library.
+    # E.g.
+    # "hexagon/udivsi3.S" => "udivsi3"
+    # "udivsi3.c" => "udivsi3"
+    get_filename_component(FILE_NAME_FILTERED "${file_name}" NAME_WE)
+    list(APPEND BUILTINS_LIT_SOURCE_FEATURES "crt_has_${FILE_NAME_FILTERED}")
+  endforeach()
+
   string(TOUPPER ${arch} ARCH_UPPER_CASE)
   set(CONFIG_NAME ${ARCH_UPPER_CASE}${OS_NAME}Config)
   configure_lit_site_cfg(
Index: test/builtins/Unit/comparedf2_test.c
===================================================================
--- test/builtins/Unit/comparedf2_test.c
+++ test/builtins/Unit/comparedf2_test.c
@@ -1,4 +1,5 @@
 // RUN: %clang_builtins %s %librt -o %t && %run %t
+// REQUIRES: crt_has_comparedf2
 
 //===-- cmpdf2_test.c - Test __cmpdf2 -------------------------------------===//
 //
Index: test/builtins/Unit/comparesf2_test.c
===================================================================
--- test/builtins/Unit/comparesf2_test.c
+++ test/builtins/Unit/comparesf2_test.c
@@ -1,4 +1,5 @@
 // RUN: %clang_builtins %s %librt -o %t && %run %t
+// REQUIRES: crt_has_comparesf2
 
 //===-- cmpsf2_test.c - Test __cmpsf2 -------------------------------------===//
 //
Index: test/builtins/Unit/divdf3_test.c
===================================================================
--- test/builtins/Unit/divdf3_test.c
+++ test/builtins/Unit/divdf3_test.c
@@ -1,4 +1,5 @@
 // RUN: %clang_builtins %s %librt -o %t && %run %t
+// REQUIRES: crt_has_divdf3
 //===--------------- divdf3_test.c - Test __divdf3 ------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
Index: test/builtins/Unit/divmodsi4_test.c
===================================================================
--- test/builtins/Unit/divmodsi4_test.c
+++ test/builtins/Unit/divmodsi4_test.c
@@ -1,4 +1,5 @@
 // RUN: %clang_builtins %s %librt -o %t && %run %t
+// REQUIRES: crt_has_divmodsi4
 //===-- divmodsi4_test.c - Test __divmodsi4 -------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
Index: test/builtins/Unit/divsf3_test.c
===================================================================
--- test/builtins/Unit/divsf3_test.c
+++ test/builtins/Unit/divsf3_test.c
@@ -1,4 +1,5 @@
 // RUN: %clang_builtins %s %librt -o %t && %run %t
+// REQUIRES: crt_has_divsf3
 //===--------------- divsf3_test.c - Test __divsf3 ------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
Index: test/builtins/Unit/divsi3_test.c
===================================================================
--- test/builtins/Unit/divsi3_test.c
+++ test/builtins/Unit/divsi3_test.c
@@ -1,4 +1,5 @@
 // RUN: %clang_builtins %s %librt -o %t && %run %t
+// REQUIRES: crt_has_divsi3
 //===-- divsi3_test.c - Test __divsi3 -------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
Index: test/builtins/Unit/lit.cfg.py
===================================================================
--- test/builtins/Unit/lit.cfg.py
+++ test/builtins/Unit/lit.cfg.py
@@ -94,3 +94,7 @@
 
 if not config.emulator:
   config.available_features.add('native-run')
+
+# Add features for available sources
+builtins_source_features = config.builtins_lit_source_features.split(';')
+config.available_features.update(builtins_source_features)
Index: test/builtins/Unit/lit.site.cfg.py.in
===================================================================
--- test/builtins/Unit/lit.site.cfg.py.in
+++ test/builtins/Unit/lit.site.cfg.py.in
@@ -6,6 +6,8 @@
 config.target_arch = "@BUILTINS_TEST_TARGET_ARCH@"
 config.is_msvc = @MSVC_PYBOOL@
 config.builtins_is_msvc = @BUILTINS_IS_MSVC_PYBOOL@
+config.builtins_lit_source_features = "@BUILTINS_LIT_SOURCE_FEATURES@"
+
 # Load common config for all compiler-rt lit tests.
 lit_config.load_config(config, "@COMPILER_RT_BINARY_DIR@/test/lit.common.configured")
 
Index: test/builtins/Unit/modsi3_test.c
===================================================================
--- test/builtins/Unit/modsi3_test.c
+++ test/builtins/Unit/modsi3_test.c
@@ -1,4 +1,5 @@
 // RUN: %clang_builtins %s %librt -o %t && %run %t
+// REQUIRES: crt_has_modsi3
 /* ===-- modsi3_test.c - Test __modsi3 -------------------------------------===
  *
  * Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
Index: test/builtins/Unit/truncdfsf2_test.c
===================================================================
--- test/builtins/Unit/truncdfsf2_test.c
+++ test/builtins/Unit/truncdfsf2_test.c
@@ -1,4 +1,5 @@
 // RUN: %clang_builtins %s %librt -o %t && %run %t
+// REQUIRES: crt_has_truncdfsf2
 
 //===--------------- truncdfsf2_test.c - Test __truncdfsf2 ----------------===//
 //
Index: test/builtins/Unit/udivmodsi4_test.c
===================================================================
--- test/builtins/Unit/udivmodsi4_test.c
+++ test/builtins/Unit/udivmodsi4_test.c
@@ -1,4 +1,5 @@
 // RUN: %clang_builtins %s %librt -o %t && %run %t
+// REQUIRES: crt_has_udivmodsi4
 //===-- udivmodsi4_test.c - Test __udivmodsi4 -----------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
Index: test/builtins/Unit/udivsi3_test.c
===================================================================
--- test/builtins/Unit/udivsi3_test.c
+++ test/builtins/Unit/udivsi3_test.c
@@ -1,4 +1,5 @@
 // RUN: %clang_builtins %s %librt -o %t && %run %t
+// REQUIRES: crt_has_udivsi3
 //===-- udivsi3_test.c - Test __udivsi3 -----------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
Index: test/builtins/Unit/umodsi3_test.c
===================================================================
--- test/builtins/Unit/umodsi3_test.c
+++ test/builtins/Unit/umodsi3_test.c
@@ -1,4 +1,5 @@
 // RUN: %clang_builtins %s %librt -o %t && %run %t
+// REQUIRES: crt_has_umodsi3
 //===-- umodsi3_test.c - Test __umodsi3 -----------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.