Index: lib/Target/AArch64/AArch64AsmPrinter.cpp
===================================================================
--- lib/Target/AArch64/AArch64AsmPrinter.cpp
+++ lib/Target/AArch64/AArch64AsmPrinter.cpp
@@ -276,6 +276,11 @@
     printOffset(MO.getOffset(), O);
     break;
   }
+  case MachineOperand::MO_BlockAddress: {
+    MCSymbol *Sym = GetBlockAddressSymbol(MO.getBlockAddress());
+    Sym->print(O, MAI);
+    break;
+  }
   }
 }
 
Index: lib/Target/AArch64/AArch64ISelLowering.cpp
===================================================================
--- lib/Target/AArch64/AArch64ISelLowering.cpp
+++ lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -5207,7 +5207,7 @@
 
 // Table of Constraints
 // TODO: This is the current set of constraints supported by ARM for the
-// compiler, not all of them may make sense, e.g. S may be difficult to support.
+// compiler, not all of them may make sense.
 //
 // r - A general register
 // w - An FP/SIMD register of some size in the range v0-v31
@@ -5267,6 +5267,8 @@
     // currently handle addresses it is the same as 'r'.
     case 'Q':
       return C_Memory;
+    case 'S': // A symbolic address
+      return C_Other;
     }
   }
   return TargetLowering::getConstraintType(Constraint);
@@ -5391,6 +5393,23 @@
       Result = DAG.getRegister(AArch64::WZR, MVT::i32);
     break;
   }
+  case 'S': {
+    // An absolute symbolic address or label reference.
+    if (const GlobalAddressSDNode *GA = dyn_cast<GlobalAddressSDNode>(Op)) {
+      Result = DAG.getTargetGlobalAddress(GA->getGlobal(), SDLoc(Op),
+                                          GA->getValueType(0));
+    } else if (const BlockAddressSDNode *BA =
+                   dyn_cast<BlockAddressSDNode>(Op)) {
+      Result =
+          DAG.getTargetBlockAddress(BA->getBlockAddress(), BA->getValueType(0));
+    } else if (const ExternalSymbolSDNode *ES =
+                   dyn_cast<ExternalSymbolSDNode>(Op)) {
+      Result =
+          DAG.getTargetExternalSymbol(ES->getSymbol(), ES->getValueType(0));
+    } else
+      return;
+    break;
+  }
 
   case 'I':
   case 'J':
Index: test/CodeGen/AArch64/inlineasm-S-constraint.ll
===================================================================
--- /dev/null
+++ test/CodeGen/AArch64/inlineasm-S-constraint.ll
@@ -0,0 +1,20 @@
+;RUN: llc -mtriple=aarch64-none-linux-gnu -mattr=+neon < %s | FileCheck %s
+@var = global i32 0
+define void @test_inline_constraint_S() {
+; CHECK-LABEL: test_inline_constraint_S:
+  call void asm sideeffect "adrp x0, $0", "S"(i32* @var)
+  call void asm sideeffect "add x0, x0, :lo12:$0", "S"(i32* @var)
+; CHECK: adrp x0, var
+; CHECK: add x0, x0, :lo12:var
+  ret void
+}
+define i32 @test_inline_constraint_S_label(i1 %in) {
+; CHECK-LABEL: test_inline_constraint_S_label:
+  call void asm sideeffect "adr x0, $0", "S"(i8* blockaddress(@test_inline_constraint_S_label, %loc))
+; CHECK: adr x0, .Ltmp{{[0-9]+}}
+br i1 %in, label %loc, label %loc2
+loc:
+  ret i32 0
+loc2:
+  ret i32 42
+}