diff --git a/llvm/lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp b/llvm/lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp
--- a/llvm/lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp
@@ -601,7 +601,8 @@
 
 /// PrintAsmOperand - Print the specified operand of MI, an INLINEASM
 /// instruction, using the specified assembler variant.  Targets should
-/// override this to format as appropriate.
+/// override this to format as appropriate for machine specific ExtraCodes
+/// or when the arch-independent handling would be too complex otherwise.
 bool AsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
                                  const char *ExtraCode, raw_ostream &O) {
   // Does this asm operand have a single letter operand modifier?
@@ -613,18 +614,24 @@
     switch (ExtraCode[0]) {
     default:
       return true;  // Unknown modifier.
+    case 'a': // Print as memory address.
+      if (MO.isReg()) {
+        PrintAsmMemoryOperand(MI, OpNo, nullptr, O);
+        return false;
+      }
+      LLVM_FALLTHROUGH; // GCC allows '%a' to behave like '%c' with immediates.
     case 'c': // Substitute immediate value without immediate syntax
-      if (MO.getType() != MachineOperand::MO_Immediate)
+      if (!MO.isImm())
         return true;
       O << MO.getImm();
       return false;
     case 'n':  // Negate the immediate constant.
-      if (MO.getType() != MachineOperand::MO_Immediate)
+      if (!MO.isImm())
         return true;
       O << -MO.getImm();
       return false;
     case 's':  // The GCC deprecated s modifier
-      if (MO.getType() != MachineOperand::MO_Immediate)
+      if (!MO.isImm())
         return true;
       O << ((32 - MO.getImm()) & 31);
       return false;
diff --git a/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp b/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
--- a/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
+++ b/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
@@ -504,9 +504,6 @@
     switch (ExtraCode[0]) {
     default:
       return true; // Unknown modifier.
-    case 'a':      // Print 'a' modifier
-      PrintAsmMemoryOperand(MI, OpNum, ExtraCode, O);
-      return false;
     case 'w':      // Print W register
     case 'x':      // Print X register
       if (MO.isReg())
diff --git a/llvm/lib/Target/ARM/ARMAsmPrinter.cpp b/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
--- a/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
+++ b/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
@@ -264,17 +264,6 @@
     default:
       // See if this is a generic print operand
       return AsmPrinter::PrintAsmOperand(MI, OpNum, ExtraCode, O);
-    case 'a': // Print as a memory address.
-      if (MI->getOperand(OpNum).isReg()) {
-        O << "["
-          << ARMInstPrinter::getRegisterName(MI->getOperand(OpNum).getReg())
-          << "]";
-        return false;
-      } else if (MI->getOperand(OpNum).isImm()) {
-        O << MI->getOperand(OpNum).getImm();
-        return false;
-      }
-      return true;
     case 'P': // Print a VFP double precision register.
     case 'q': // Print a NEON quad precision register.
       printOperand(MI, OpNum, O);