Index: include/llvm/IR/CallingConv.h
===================================================================
--- include/llvm/IR/CallingConv.h
+++ include/llvm/IR/CallingConv.h
@@ -69,6 +69,14 @@
     // (almost) all registers.
     PreserveAll = 15,
 
+    // Explicit - Calling convention for functions which are not full functions,
+    // instead they are code fragments where the arguments are hardware
+    // registers. They are intended to be used to generate code which can be
+    // inserted into to shadow of patchpoints and stackmaps.  The
+    // llvm.return_with_registers intrinsic is typically used to exit the
+    // function.
+    Explicit = 16,
+
     // Target - This is the start of the target-specific calling conventions,
     // e.g. fastcall and thiscall on X86.
     FirstTargetCC = 64,
Index: lib/AsmParser/LLLexer.cpp
===================================================================
--- lib/AsmParser/LLLexer.cpp
+++ lib/AsmParser/LLLexer.cpp
@@ -583,6 +583,7 @@
   KEYWORD(x86_64_win64cc);
   KEYWORD(webkit_jscc);
   KEYWORD(anyregcc);
+  KEYWORD(explicitcc);
   KEYWORD(preserve_mostcc);
   KEYWORD(preserve_allcc);
   KEYWORD(ghccc);
Index: lib/AsmParser/LLParser.cpp
===================================================================
--- lib/AsmParser/LLParser.cpp
+++ lib/AsmParser/LLParser.cpp
@@ -1434,6 +1434,7 @@
 ///   ::= 'x86_64_win64cc'
 ///   ::= 'webkit_jscc'
 ///   ::= 'anyregcc'
+///   ::= 'explicitcc'
 ///   ::= 'preserve_mostcc'
 ///   ::= 'preserve_allcc'
 ///   ::= 'ghccc'
@@ -1462,6 +1463,7 @@
   case lltok::kw_x86_64_win64cc: CC = CallingConv::X86_64_Win64; break;
   case lltok::kw_webkit_jscc:    CC = CallingConv::WebKit_JS; break;
   case lltok::kw_anyregcc:       CC = CallingConv::AnyReg; break;
+  case lltok::kw_explicitcc:     CC = CallingConv::Explicit; break;
   case lltok::kw_preserve_mostcc:CC = CallingConv::PreserveMost; break;
   case lltok::kw_preserve_allcc: CC = CallingConv::PreserveAll; break;
   case lltok::kw_ghccc:          CC = CallingConv::GHC; break;
Index: lib/AsmParser/LLToken.h
===================================================================
--- lib/AsmParser/LLToken.h
+++ lib/AsmParser/LLToken.h
@@ -93,7 +93,7 @@
     kw_ptx_kernel, kw_ptx_device,
     kw_spir_kernel, kw_spir_func,
     kw_x86_64_sysvcc, kw_x86_64_win64cc,
-    kw_webkit_jscc, kw_anyregcc,
+    kw_webkit_jscc, kw_anyregcc, kw_explicitcc,
     kw_preserve_mostcc, kw_preserve_allcc,
     kw_ghccc,
 
Index: lib/IR/AsmWriter.cpp
===================================================================
--- lib/IR/AsmWriter.cpp
+++ lib/IR/AsmWriter.cpp
@@ -296,6 +296,7 @@
   case CallingConv::Cold:          Out << "coldcc"; break;
   case CallingConv::WebKit_JS:     Out << "webkit_jscc"; break;
   case CallingConv::AnyReg:        Out << "anyregcc"; break;
+  case CallingConv::Explicit:      Out << "explicitcc"; break;
   case CallingConv::PreserveMost:  Out << "preserve_mostcc"; break;
   case CallingConv::PreserveAll:   Out << "preserve_allcc"; break;
   case CallingConv::GHC:           Out << "ghccc"; break;