Index: llvm/trunk/lib/Target/RISCV/RISCVRegisterInfo.td
===================================================================
--- llvm/trunk/lib/Target/RISCV/RISCVRegisterInfo.td
+++ llvm/trunk/lib/Target/RISCV/RISCVRegisterInfo.td
@@ -55,7 +55,7 @@
   def X6  : RISCVReg<6, "x6", ["t1"]>, DwarfRegNum<[6]>;
   def X7  : RISCVReg<7, "x7", ["t2"]>, DwarfRegNum<[7]>;
   }
-  def X8  : RISCVReg<8, "x8", ["s0"]>, DwarfRegNum<[8]>;
+  def X8  : RISCVReg<8, "x8", ["s0", "fp"]>, DwarfRegNum<[8]>;
   def X9  : RISCVReg<9, "x9", ["s1"]>, DwarfRegNum<[9]>;
   def X10 : RISCVReg<10,"x10", ["a0"]>, DwarfRegNum<[10]>;
   def X11 : RISCVReg<11,"x11", ["a1"]>, DwarfRegNum<[11]>;
Index: llvm/trunk/test/MC/RISCV/rvi-alternate-abi-names.s
===================================================================
--- llvm/trunk/test/MC/RISCV/rvi-alternate-abi-names.s
+++ llvm/trunk/test/MC/RISCV/rvi-alternate-abi-names.s
@@ -0,0 +1,16 @@
+# RUN: llvm-mc %s -triple=riscv32 \
+# RUN:     | FileCheck %s
+# RUN: llvm-mc %s -triple=riscv64 \
+# RUN:     | FileCheck %s
+# RUN: llvm-mc -filetype=obj -triple riscv32 < %s \
+# RUN:     | llvm-objdump -d -r - \
+# RUN:     | FileCheck %s
+# RUN: llvm-mc -filetype=obj -triple riscv64 < %s \
+# RUN:     | llvm-objdump -d -r - \
+# RUN:     | FileCheck %s
+
+# 'fp' is an alternate ABI name for 's0' and it should be accepted in input.
+# However, 's0' should be printed in preference.
+
+# CHECK: addi s0, s0, -4
+addi fp, fp, -4