Index: llvm/trunk/CMakeLists.txt
===================================================================
--- llvm/trunk/CMakeLists.txt
+++ llvm/trunk/CMakeLists.txt
@@ -414,6 +414,9 @@
 set(LLVM_ABI_BREAKING_CHECKS "WITH_ASSERTS" CACHE STRING
   "Enable abi-breaking checks.  Can be WITH_ASSERTS, FORCE_ON or FORCE_OFF.")
 
+option(LLVM_DISABLE_ABI_BREAKING_CHECKS_ENFORCING
+  "Disable abi-breaking checks mismatch detection at link-tim." OFF)
+
 option(LLVM_FORCE_USE_OLD_HOST_TOOLCHAIN
        "Set to ON to force using an old, unsupported host toolchain." OFF)
 
Index: llvm/trunk/include/llvm/Config/abi-breaking.h.cmake
===================================================================
--- llvm/trunk/include/llvm/Config/abi-breaking.h.cmake
+++ llvm/trunk/include/llvm/Config/abi-breaking.h.cmake
@@ -15,6 +15,11 @@
 /* Define to enable checks that alter the LLVM C++ ABI */
 #cmakedefine01 LLVM_ENABLE_ABI_BREAKING_CHECKS
 
+/* Define to disable the link-time checking of mismatch for
+   LLVM_ENABLE_ABI_BREAKING_CHECKS */
+#cmakedefine01 LLVM_DISABLE_ABI_BREAKING_CHECKS_ENFORCING
+#if !LLVM_DISABLE_ABI_BREAKING_CHECKS_ENFORCING
+
 // ABI_BREAKING_CHECKS protection: provides link-time failure when clients build
 // mismatch with LLVM
 #if defined(_MSC_VER)
@@ -38,4 +43,6 @@
 }
 #endif // _MSC_VER
 
+#endif // LLVM_DISABLE_ABI_BREAKING_CHECKS_ENFORCING
+
 #endif