diff --git a/cmake/compilerconfig.cmake b/cmake/compilerconfig.cmake
index 91141b1b..4e4f5fae 100644
--- a/cmake/compilerconfig.cmake
+++ b/cmake/compilerconfig.cmake
@@ -12,7 +12,7 @@ set(CMAKE_EXE_LINKER_FLAGS "-Wl,-gc-sections")
 
 set(CMAKE_C_COMPILER "gcc")
 set(CMAKE_CXX_COMPILER "ag++")
-set(CMAKE_AGPP_FLAGS "--real-instances" CACHE STRING "Additional ag++ flags, e.g. --real-instances --keep_woven")
+set(CMAKE_AGPP_FLAGS "-D__NO_MATH_INLINES" CACHE STRING "Additional ag++ flags (space-separated), e.g., --keep_woven")
   ## Here we add the build dir holding the generated header files (protobuf)
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} --Xweaver -p ${PROJECT_SOURCE_DIR}/src -p ${PROJECT_SOURCE_DIR}/simulators -p ${PROJECT_SOURCE_DIR}/debuggers -p ${PROJECT_SOURCE_DIR}/tools -p ${PROJECT_BINARY_DIR}/src ${CMAKE_AGPP_FLAGS} --Xcompiler")
 
diff --git a/doc/how-to-build.txt b/doc/how-to-build.txt
index 5622867e..218f1fb9 100644
--- a/doc/how-to-build.txt
+++ b/doc/how-to-build.txt
@@ -19,6 +19,8 @@ Required for Fail*:
    obtained from <http://www.aspectc.org>; nightlies can be downloaded from
    <http://akut.aspectc.org>.  Make sure you use the 64-bit version if running
    in a 64-bit environment.
+   * AspectC++ >1.2 (clang-based AspectC++): build with CMAKE_AGPP_FLAGS
+     "-D__NO_MATH_INLINES" or "--c_compiler clang++"
  - optional:
    * LLVM 3.3 or 3.4 (needed for several importers in tools/import-trace)
      (compiles/links with 3.1 or 3.2, but fails to properly import information