Index: lib/Target/AArch64/AArch64AsmPrinter.cpp
===================================================================
--- lib/Target/AArch64/AArch64AsmPrinter.cpp
+++ lib/Target/AArch64/AArch64AsmPrinter.cpp
@@ -320,6 +320,9 @@
     switch (ExtraCode[0]) {
     default:
       return true; // Unknown modifier.
+    case 'a':      // Print 'a' modifier
+      PrintAsmMemoryOperand(MI, OpNum, AsmVariant, ExtraCode, O);
+      return false;
     case 'w':      // Print W register
     case 'x':      // Print X register
       if (MO.isReg())
@@ -388,7 +391,7 @@
                                               unsigned AsmVariant,
                                               const char *ExtraCode,
                                               raw_ostream &O) {
-  if (ExtraCode && ExtraCode[0])
+  if (ExtraCode && ExtraCode[0] && ExtraCode[0] != 'a')
     return true; // Unknown modifier.
 
   const MachineOperand &MO = MI->getOperand(OpNum);
Index: test/CodeGen/AArch64/arm64-inline-asm.ll
===================================================================
--- test/CodeGen/AArch64/arm64-inline-asm.ll
+++ test/CodeGen/AArch64/arm64-inline-asm.ll
@@ -254,3 +254,10 @@
   tail call void asm sideeffect "sqxtn h0, ${0:s}\0A", "w"(i32 %a)
   ret void
 }
+
+define void @test_inline_modifier_a(i8* %ptr) nounwind {
+  ; CHECK-LABEL: test_inline_modifier_a:
+  tail call void asm sideeffect "prfm pldl1keep, ${0:a}\0A", "r"(i8* %ptr)
+  ; CHECK: prfm pldl1keep, [x0]
+  ret void
+}