Index: include/clang/Basic/Builtins.def
===================================================================
--- include/clang/Basic/Builtins.def
+++ include/clang/Basic/Builtins.def
@@ -953,6 +953,7 @@
 LIBBUILTIN(index, "c*cC*i",       "f",     "strings.h", ALL_GNU_LANGUAGES)
 LIBBUILTIN(rindex, "c*cC*i",      "f",     "strings.h", ALL_GNU_LANGUAGES)
 LIBBUILTIN(bzero, "vv*z",         "f",     "strings.h", ALL_GNU_LANGUAGES)
+LIBBUILTIN(bcmp, "iv*v*z",        "f",     "strings.h", ALL_GNU_LANGUAGES)
 // In some systems str[n]casejmp is a macro that expands to _str[n]icmp.
 // We undefine then here to avoid wrong name.
 #undef strcasecmp
Index: lib/AST/Decl.cpp
===================================================================
--- lib/AST/Decl.cpp
+++ lib/AST/Decl.cpp
@@ -3672,6 +3672,10 @@
   case Builtin::BImemcmp:
     return Builtin::BImemcmp;
 
+  case Builtin::BI__builtin_bcmp:
+  case Builtin::BIbcmp:
+    return Builtin::BIbcmp;
+
   case Builtin::BI__builtin_strncpy:
   case Builtin::BI__builtin___strncpy_chk:
   case Builtin::BIstrncpy:
@@ -3712,6 +3716,8 @@
         return Builtin::BImemmove;
       else if (FnInfo->isStr("memcmp"))
         return Builtin::BImemcmp;
+      else if (FnInfo->isStr("bcmp"))
+        return Builtin::BIbcmp;
       else if (FnInfo->isStr("strncpy"))
         return Builtin::BIstrncpy;
       else if (FnInfo->isStr("strncmp"))
Index: lib/AST/ExprConstant.cpp
===================================================================
--- lib/AST/ExprConstant.cpp
+++ lib/AST/ExprConstant.cpp
@@ -8426,6 +8426,7 @@
   case Builtin::BIstrncmp:
   case Builtin::BIwcsncmp:
   case Builtin::BImemcmp:
+  case Builtin::BIbcmp:
   case Builtin::BIwmemcmp:
     // A call to strlen is not a constant expression.
     if (Info.getLangOpts().CPlusPlus11)
@@ -8440,6 +8441,7 @@
   case Builtin::BI__builtin_strncmp:
   case Builtin::BI__builtin_wcsncmp:
   case Builtin::BI__builtin_memcmp:
+  case Builtin::BI__builtin_bcmp:
   case Builtin::BI__builtin_wmemcmp: {
     LValue String1, String2;
     if (!EvaluatePointer(E->getArg(0), String1, Info) ||
@@ -8470,7 +8472,9 @@
     QualType CharTy2 = String2.Designator.getType(Info.Ctx);
 
     bool IsRawByte = BuiltinOp == Builtin::BImemcmp ||
-                     BuiltinOp == Builtin::BI__builtin_memcmp;
+                     BuiltinOp == Builtin::BIbcmp ||
+                     BuiltinOp == Builtin::BI__builtin_memcmp ||
+                     BuiltinOp == Builtin::BI__builtin_bcmp;
 
     assert(IsRawByte ||
            (Info.Ctx.hasSameUnqualifiedType(
@@ -8538,10 +8542,12 @@
       return Success(0, E);
     }
 
-    bool StopAtNull = (BuiltinOp != Builtin::BImemcmp &&
-                       BuiltinOp != Builtin::BIwmemcmp &&
-                       BuiltinOp != Builtin::BI__builtin_memcmp &&
-                       BuiltinOp != Builtin::BI__builtin_wmemcmp);
+    bool StopAtNull =
+        (BuiltinOp != Builtin::BImemcmp && BuiltinOp != Builtin::BIbcmp &&
+         BuiltinOp != Builtin::BIwmemcmp &&
+         BuiltinOp != Builtin::BI__builtin_memcmp &&
+         BuiltinOp != Builtin::BI__builtin_bcmp &&
+         BuiltinOp != Builtin::BI__builtin_wmemcmp);
     bool IsWide = BuiltinOp == Builtin::BIwcscmp ||
                   BuiltinOp == Builtin::BIwcsncmp ||
                   BuiltinOp == Builtin::BIwmemcmp ||
Index: lib/Sema/SemaChecking.cpp
===================================================================
--- lib/Sema/SemaChecking.cpp
+++ lib/Sema/SemaChecking.cpp
@@ -9174,23 +9174,23 @@
             getContainedDynamicClass(PointeeTy, IsContained)) {
 
       unsigned OperationType = 0;
+      const bool IsCmp = BId == Builtin::BImemcmp || BId == Builtin::BIbcmp;
       // "overwritten" if we're warning about the destination for any call
       // but memcmp; otherwise a verb appropriate to the call.
-      if (ArgIdx != 0 || BId == Builtin::BImemcmp) {
+      if (ArgIdx != 0 || IsCmp) {
         if (BId == Builtin::BImemcpy)
           OperationType = 1;
         else if(BId == Builtin::BImemmove)
           OperationType = 2;
-        else if (BId == Builtin::BImemcmp)
+        else if (IsCmp)
           OperationType = 3;
       }
 
-      DiagRuntimeBehavior(
-        Dest->getExprLoc(), Dest,
-        PDiag(diag::warn_dyn_class_memaccess)
-          << (BId == Builtin::BImemcmp ? ArgIdx + 2 : ArgIdx)
-          << FnName << IsContained << ContainedRD << OperationType
-          << Call->getCallee()->getSourceRange());
+      DiagRuntimeBehavior(Dest->getExprLoc(), Dest,
+                          PDiag(diag::warn_dyn_class_memaccess)
+                              << (IsCmp ? ArgIdx + 2 : ArgIdx) << FnName
+                              << IsContained << ContainedRD << OperationType
+                              << Call->getCallee()->getSourceRange());
     } else if (PointeeTy.hasNonTrivialObjCLifetime() &&
              BId != Builtin::BImemset)
       DiagRuntimeBehavior(