Index: llvm/trunk/include/llvm/IR/CallingConv.h
===================================================================
--- llvm/trunk/include/llvm/IR/CallingConv.h
+++ llvm/trunk/include/llvm/IR/CallingConv.h
@@ -220,6 +220,9 @@
     /// shader if tessellation is in use, or otherwise the vertex shader.
     AMDGPU_ES = 96,
 
+    // Calling convention between AArch64 Advanced SIMD functions
+    AArch64_VectorCall = 97,
+
     /// The highest possible calling convention ID. Must be some 2^k - 1.
     MaxID = 1023
   };
Index: llvm/trunk/lib/AsmParser/LLLexer.cpp
===================================================================
--- llvm/trunk/lib/AsmParser/LLLexer.cpp
+++ llvm/trunk/lib/AsmParser/LLLexer.cpp
@@ -592,6 +592,7 @@
   KEYWORD(arm_apcscc);
   KEYWORD(arm_aapcscc);
   KEYWORD(arm_aapcs_vfpcc);
+  KEYWORD(aarch64_vector_pcs);
   KEYWORD(msp430_intrcc);
   KEYWORD(avr_intrcc);
   KEYWORD(avr_signalcc);
Index: llvm/trunk/lib/AsmParser/LLParser.cpp
===================================================================
--- llvm/trunk/lib/AsmParser/LLParser.cpp
+++ llvm/trunk/lib/AsmParser/LLParser.cpp
@@ -1874,6 +1874,7 @@
 ///   ::= 'arm_apcscc'
 ///   ::= 'arm_aapcscc'
 ///   ::= 'arm_aapcs_vfpcc'
+///   ::= 'aarch64_vector_pcs'
 ///   ::= 'msp430_intrcc'
 ///   ::= 'avr_intrcc'
 ///   ::= 'avr_signalcc'
@@ -1917,6 +1918,7 @@
   case lltok::kw_arm_apcscc:     CC = CallingConv::ARM_APCS; break;
   case lltok::kw_arm_aapcscc:    CC = CallingConv::ARM_AAPCS; break;
   case lltok::kw_arm_aapcs_vfpcc:CC = CallingConv::ARM_AAPCS_VFP; break;
+  case lltok::kw_aarch64_vector_pcs:CC = CallingConv::AArch64_VectorCall; break;
   case lltok::kw_msp430_intrcc:  CC = CallingConv::MSP430_INTR; break;
   case lltok::kw_avr_intrcc:     CC = CallingConv::AVR_INTR; break;
   case lltok::kw_avr_signalcc:   CC = CallingConv::AVR_SIGNAL; break;
Index: llvm/trunk/lib/AsmParser/LLToken.h
===================================================================
--- llvm/trunk/lib/AsmParser/LLToken.h
+++ llvm/trunk/lib/AsmParser/LLToken.h
@@ -139,6 +139,7 @@
   kw_arm_apcscc,
   kw_arm_aapcscc,
   kw_arm_aapcs_vfpcc,
+  kw_aarch64_vector_pcs,
   kw_msp430_intrcc,
   kw_avr_intrcc,
   kw_avr_signalcc,
Index: llvm/trunk/lib/IR/AsmWriter.cpp
===================================================================
--- llvm/trunk/lib/IR/AsmWriter.cpp
+++ llvm/trunk/lib/IR/AsmWriter.cpp
@@ -363,6 +363,7 @@
   case CallingConv::ARM_APCS:      Out << "arm_apcscc"; break;
   case CallingConv::ARM_AAPCS:     Out << "arm_aapcscc"; break;
   case CallingConv::ARM_AAPCS_VFP: Out << "arm_aapcs_vfpcc"; break;
+  case CallingConv::AArch64_VectorCall: Out << "aarch64_vector_pcs"; break;
   case CallingConv::MSP430_INTR:   Out << "msp430_intrcc"; break;
   case CallingConv::AVR_INTR:      Out << "avr_intrcc "; break;
   case CallingConv::AVR_SIGNAL:    Out << "avr_signalcc "; break;
Index: llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.cpp
===================================================================
--- llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -2896,6 +2896,8 @@
     return IsVarArg ? CC_AArch64_DarwinPCS_VarArg : CC_AArch64_DarwinPCS;
   case CallingConv::Win64:
     return IsVarArg ? CC_AArch64_Win64_VarArg : CC_AArch64_AAPCS;
+  case CallingConv::AArch64_VectorCall:
+    return CC_AArch64_AAPCS;
   }
 }
 
Index: llvm/trunk/lib/Target/AArch64/AArch64RegisterInfo.cpp
===================================================================
--- llvm/trunk/lib/Target/AArch64/AArch64RegisterInfo.cpp
+++ llvm/trunk/lib/Target/AArch64/AArch64RegisterInfo.cpp
@@ -49,6 +49,9 @@
     return CSR_AArch64_NoRegs_SaveList;
   if (MF->getFunction().getCallingConv() == CallingConv::AnyReg)
     return CSR_AArch64_AllRegs_SaveList;
+  if (MF->getFunction().getCallingConv() == CallingConv::AArch64_VectorCall)
+    // FIXME: default to AAPCS until we add full support.
+    return CSR_AArch64_AAPCS_SaveList;
   if (MF->getFunction().getCallingConv() == CallingConv::CXX_FAST_TLS)
     return MF->getInfo<AArch64FunctionInfo>()->isSplitCSR() ?
            CSR_AArch64_CXX_TLS_Darwin_PE_SaveList :
@@ -98,6 +101,9 @@
   if (CC == CallingConv::CXX_FAST_TLS)
     return SCS ? CSR_AArch64_CXX_TLS_Darwin_SCS_RegMask
                : CSR_AArch64_CXX_TLS_Darwin_RegMask;
+  if (CC == CallingConv::AArch64_VectorCall)
+    // FIXME: default to AAPCS until we add full support.
+    return SCS ? CSR_AArch64_AAPCS_SCS_RegMask : CSR_AArch64_AAPCS_RegMask;
   if (MF.getSubtarget<AArch64Subtarget>().getTargetLowering()
           ->supportSwiftError() &&
       MF.getFunction().getAttributes().hasAttrSomewhere(Attribute::SwiftError))
Index: llvm/trunk/test/Bitcode/vector-pcs.ll
===================================================================
--- llvm/trunk/test/Bitcode/vector-pcs.ll
+++ llvm/trunk/test/Bitcode/vector-pcs.ll
@@ -0,0 +1,11 @@
+; RUN: llvm-as %s -o - -f | llvm-dis | FileCheck %s
+; RUN: llvm-as %s -o - -f | verify-uselistorder
+
+declare aarch64_vector_pcs void @aarch64_vector_pcs()
+; CHECK: declare aarch64_vector_pcs void @aarch64_vector_pcs
+
+define void @call_aarch64_vector_pcs() {
+; CHECK: call aarch64_vector_pcs void @aarch64_vector_pcs
+  call aarch64_vector_pcs void @aarch64_vector_pcs()
+  ret void
+}