diff --git a/lib/Target/ARM/AsmParser/ARMAsmParser.cpp b/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
index 830e9c0b3b7..68f128189f2 100644
--- a/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ b/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -3260,7 +3260,7 @@ parseMemBarrierOptOperand(SmallVectorImpl<MCParsedAsmOperand*> &Operands) {
     return MatchOperand_NoMatch;
   StringRef OptStr = Tok.getString();
 
-  unsigned Opt = StringSwitch<unsigned>(OptStr.slice(0, OptStr.size()))
+  unsigned Opt = StringSwitch<unsigned>(OptStr.slice(0, OptStr.size()).lower())
     .Case("sy",    ARM_MB::SY)
     .Case("st",    ARM_MB::ST)
     .Case("sh",    ARM_MB::ISH)
diff --git a/test/MC/ARM/basic-arm-instructions.s b/test/MC/ARM/basic-arm-instructions.s
index 0920d715d5d..c62413d0ea9 100644
--- a/test/MC/ARM/basic-arm-instructions.s
+++ b/test/MC/ARM/basic-arm-instructions.s
@@ -601,6 +601,12 @@ Lforward:
 @ CHECK: dsb	oshst                   @ encoding: [0x42,0xf0,0x7f,0xf5]
 @ CHECK: dsb	sy                      @ encoding: [0x4f,0xf0,0x7f,0xf5]
 
+@ With capitals
+        dsb SY
+        dsb OSHST
+
+@ CHECK: dsb	sy                      @ encoding: [0x4f,0xf0,0x7f,0xf5]
+@ CHECK: dsb	oshst                   @ encoding: [0x42,0xf0,0x7f,0xf5]
 @------------------------------------------------------------------------------
 @ EOR
 @------------------------------------------------------------------------------