Index: lib/Target/RISCV/RISCVInstrInfo.td
===================================================================
--- lib/Target/RISCV/RISCVInstrInfo.td
+++ lib/Target/RISCV/RISCVInstrInfo.td
@@ -574,3 +574,42 @@
 include "RISCVInstrInfoA.td"
 include "RISCVInstrInfoF.td"
 include "RISCVInstrInfoD.td"
+
+//===----------------------------------------------------------------------===//
+// Privileged instructions
+//===----------------------------------------------------------------------===//
+
+let hasSideEffects = 1, mayLoad = 0, mayStore = 0 in
+class Prv_ri<string opcodestr>
+    : RVInstI<0b000, OPC_SYSTEM, (outs), (ins), opcodestr, "">;
+
+def URET : Prv_ri<"uret"> {
+  let rs1 = 0;
+  let rd = 0;
+  let imm12 = 0b000000000010;
+}
+
+def SRET : Prv_ri<"sret"> {
+  let rs1 = 0;
+  let rd = 0;
+  let imm12 = 0b000100000010;
+}
+
+def MRET : Prv_ri<"mret"> {
+  let rs1 = 0;
+  let rd = 0;
+  let imm12 = 0b001100000010;
+}
+
+def WFI : Prv_ri<"wfi"> {
+  let rs1 = 0;
+  let rd = 0;
+  let imm12 = 0b000100000101;
+}
+
+let hasSideEffects = 1, mayLoad = 0, mayStore = 0 in
+def SFENCEVM : RVInstR<0b0001001, 0b000, OPC_SYSTEM, (outs),
+                  (ins GPR:$rs1, GPR:$rs2),
+                  "sfence.vma", "$rs1, $rs2"> {
+  let rd = 0;
+}
Index: test/MC/RISCV/priv.s
===================================================================
--- /dev/null
+++ test/MC/RISCV/priv.s
@@ -0,0 +1,40 @@
+# RUN: llvm-mc %s -triple=riscv32 -show-encoding \
+# RUN:     | FileCheck -check-prefixes=CHECK,CHECK-INST %s
+# RUN: llvm-mc %s -triple=riscv64 -show-encoding \
+# RUN:     | FileCheck -check-prefixes=CHECK,CHECK-INST %s
+# RUN: llvm-mc -filetype=obj -triple riscv32 < %s \
+# RUN:     | llvm-objdump -d - | FileCheck -check-prefix=CHECK-INST %s
+# RUN: llvm-mc -filetype=obj -triple riscv64 < %s \
+# RUN:     | llvm-objdump -d - | FileCheck -check-prefix=CHECK-INST %s
+
+  # CHECK-INST: ecall
+# CHECK: encoding: [0x73,0x00,0x00,0x00]
+  ecall
+
+  # CHECK-INST: ebreak
+# CHECK: encoding: [0x73,0x00,0x10,0x00]
+  ebreak
+
+# CHECK-INST: uret
+# CHECK: encoding: [0x73,0x00,0x20,0x00]
+uret
+
+# CHECK-INST: sret
+# CHECK: encoding: [0x73,0x00,0x20,0x10]
+sret
+
+# CHECK-INST: mret
+# CHECK: encoding: [0x73,0x00,0x20,0x30]
+mret
+
+# CHECK-INST: wfi
+# CHECK: encoding: [0x73,0x00,0x50,0x10]
+wfi
+
+# CHECK-INST: sfence.vma zero, zero
+# CHECK: encoding: [0x73,0x00,0x00,0x12]
+sfence.vma zero, zero
+
+# CHECK-INST: sfence.vma a0, a1
+# CHECK: encoding: [0x73,0x00,0xb5,0x12]
+sfence.vma a0, a1