diff --git a/lib/Target/ARM/ARMInstrInfo.td b/lib/Target/ARM/ARMInstrInfo.td
index 75a109e2c3c..ee824699e76 100644
--- a/lib/Target/ARM/ARMInstrInfo.td
+++ b/lib/Target/ARM/ARMInstrInfo.td
@@ -2282,12 +2282,6 @@ let mayLoad = 1, neverHasSideEffects = 1, hasExtraDefRegAllocReq = 1 in {
   def LDRD : AI3ld<0b1101, 0, (outs GPR:$Rt, GPR:$Rt2), (ins addrmode3:$addr),
                    LdMiscFrm, IIC_iLoad_d_r, "ldrd", "\t$Rt, $Rt2, $addr", []>,
              Requires<[IsARM, HasV5TE]>;
-
-  // GNU Assembler extension (compatibility)
-  let isAsmParserOnly = 1 in
-    def LDRD_PAIR : AI3ld<0b1101, 0, (outs GPRPairOp:$Rt), (ins addrmode3:$addr),
-                          LdMiscFrm, IIC_iLoad_d_r, "ldrd", "\t$Rt, $addr", []>,
-                    Requires<[IsARM, HasV5TE]>;
 }
 
 def LDA : AIldracq<0b00, (outs GPR:$Rt), (ins addr_offset_none:$addr),
@@ -2557,14 +2551,6 @@ let mayStore = 1, neverHasSideEffects = 1, hasExtraSrcRegAllocReq = 1 in {
              Requires<[IsARM, HasV5TE]> {
     let Inst{21} = 0;
   }
-
-  // GNU Assembler extension (compatibility)
-  let isAsmParserOnly = 1 in
-    def STRD_PAIR : AI3str<0b1111, (outs), (ins GPRPairOp:$Rt, addrmode3:$addr),
-                           StMiscFrm, IIC_iStore_d_r, "strd", "\t$Rt, $addr", []>,
-                    Requires<[IsARM, HasV5TE]> {
-      let Inst{21} = 0;
-    }
 }
 
 // Indexed stores
diff --git a/lib/Target/ARM/AsmParser/ARMAsmParser.cpp b/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
index 9c57a244fdb..8550641c63d 100644
--- a/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ b/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -5404,21 +5404,24 @@ bool ARMAsmParser::ParseInstruction(ParseInstructionInfo &Info, StringRef Name,
   }
 
   // GNU Assembler extension (compatibility)
-  if ((Mnemonic == "ldrd" || Mnemonic == "strd") && !isThumb() &&
-      Operands.size() == 4) {
-    ARMOperand *Op = static_cast<ARMOperand *>(Operands[2]);
-    assert(Op->isReg() && "expected register argument");
+  if ((Mnemonic == "ldrd" || Mnemonic == "strd")) {
+    ARMOperand *Op2 = static_cast<ARMOperand *>(Operands[2]);
+    ARMOperand *Op3 = static_cast<ARMOperand *>(Operands[3]);
+    if (Op3->isMem()) {
+      assert(Op2->isReg() && "expected register argument");
 
-    unsigned SuperReg = MRI->getMatchingSuperReg(
-        Op->getReg(), ARM::gsub_0, &MRI->getRegClass(ARM::GPRPairRegClassID));
+      unsigned SuperReg = MRI->getMatchingSuperReg(
+          Op2->getReg(), ARM::gsub_0, &MRI->getRegClass(ARM::GPRPairRegClassID));
 
-    assert(SuperReg && "expected register pair");
+      assert(SuperReg && "expected register pair");
 
-    unsigned PairedReg = MRI->getSubReg(SuperReg, ARM::gsub_1);
+      unsigned PairedReg = MRI->getSubReg(SuperReg, ARM::gsub_1);
 
-    Operands.insert(Operands.begin() + 3,
-                    ARMOperand::CreateReg(PairedReg, Op->getStartLoc(),
-                                          Op->getEndLoc()));
+      Operands.insert(Operands.begin() + 3,
+                      ARMOperand::CreateReg(PairedReg,
+                                            Op2->getStartLoc(),
+                                            Op2->getEndLoc()));
+    }
   }
 
   // FIXME: As said above, this is all a pretty gross hack.  This instruction
diff --git a/test/MC/ARM/ldrd-strd-gnu-arm-bad-imm.s b/test/MC/ARM/ldrd-strd-gnu-arm-bad-imm.s
new file mode 100644
index 00000000000..fbe459c4168
--- /dev/null
+++ b/test/MC/ARM/ldrd-strd-gnu-arm-bad-imm.s
@@ -0,0 +1,9 @@
+@ RUN: not llvm-mc -triple=armv7-linux-gnueabi %s 2>&1 | FileCheck %s
+.text
+@ CHECK: error: instruction requires: thumb2
+@ CHECK:         ldrd    r0, [r0, #512]
+        ldrd    r0, [r0, #512]
+
+@ CHECK: error: instruction requires: thumb2
+@ CHECK:         strd    r0, [r0, #512]
+        strd    r0, [r0, #512]
diff --git a/test/MC/ARM/ldrd-strd-gnu-arm.s b/test/MC/ARM/ldrd-strd-gnu-arm.s
new file mode 100644
index 00000000000..57d21c7a146
--- /dev/null
+++ b/test/MC/ARM/ldrd-strd-gnu-arm.s
@@ -0,0 +1,20 @@
+@ PR18921
+@ RUN: llvm-mc -triple=armv7-linux-gnueabi -show-encoding < %s | FileCheck %s
+.text
+
+@ CHECK-NOT: .code	16
+
+
+@ CHECK: ldrd	r0, r1, [r10, #32]!     @ encoding: [0xd0,0x02,0xea,0xe1]
+@ CHECK: ldrd	r0, r1, [r10], #32      @ encoding: [0xd0,0x02,0xca,0xe0]
+@ CHECK: ldrd	r0, r1, [r10, #32]      @ encoding: [0xd0,0x02,0xca,0xe1]
+        ldrd    r0, [r10, #32]!
+        ldrd    r0, [r10], #32
+        ldrd    r0, [r10, #32]
+
+@ CHECK: strd	r0, r1, [r10, #32]!     @ encoding: [0xf0,0x02,0xea,0xe1]
+@ CHECK: strd	r0, r1, [r10], #32      @ encoding: [0xf0,0x02,0xca,0xe0]
+@ CHECK: strd	r0, r1, [r10, #32]      @ encoding: [0xf0,0x02,0xca,0xe1]
+        strd    r0, [r10, #32]!
+        strd    r0, [r10], #32
+        strd    r0, [r10, #32]
diff --git a/test/MC/ARM/ldrd-strd-gnu-thumb-bad-regs.s b/test/MC/ARM/ldrd-strd-gnu-thumb-bad-regs.s
new file mode 100644
index 00000000000..9d81a27f0ca
--- /dev/null
+++ b/test/MC/ARM/ldrd-strd-gnu-thumb-bad-regs.s
@@ -0,0 +1,10 @@
+@ RUN: not llvm-mc -triple=armv7-linux-gnueabi %s 2>&1 | FileCheck %s
+.text
+.thumb
+@ CHECK: error: invalid operand for instruction
+@ CHECK:         ldrd    r12, [r0, #512]
+        ldrd    r12, [r0, #512]
+
+@ CHECK: error: invalid operand for instruction
+@ CHECK:         strd    r12, [r0, #512]
+        strd    r12, [r0, #512]
diff --git a/test/MC/ARM/ldrd-strd-gnu-thumb.s b/test/MC/ARM/ldrd-strd-gnu-thumb.s
new file mode 100644
index 00000000000..67d2aa7f548
--- /dev/null
+++ b/test/MC/ARM/ldrd-strd-gnu-thumb.s
@@ -0,0 +1,20 @@
+@ PR18921
+@ RUN: llvm-mc -triple=armv7-linux-gnueabi -show-encoding < %s | FileCheck %s
+.text
+.thumb
+
+@ CHECK: .code	16
+
+@ CHECK: ldrd	r0, r1, [r10, #512]!    @ encoding: [0xfa,0xe9,0x80,0x01]
+@ CHECK: ldrd	r0, r1, [r10], #512     @ encoding: [0xfa,0xe8,0x80,0x01]
+@ CHECK: ldrd	r0, r1, [r10, #512]     @ encoding: [0xda,0xe9,0x80,0x01]
+        ldrd    r0, [r10, #512]!
+        ldrd    r0, [r10], #512
+        ldrd    r0, [r10, #512]
+
+@ CHECK: strd	r0, r1, [r10, #512]!    @ encoding: [0xea,0xe9,0x80,0x01]
+@ CHECK: strd	r0, r1, [r10], #512     @ encoding: [0xea,0xe8,0x80,0x01]
+@ CHECK: strd	r0, r1, [r10, #512]     @ encoding: [0xca,0xe9,0x80,0x01]
+        strd    r0, [r10, #512]!
+        strd    r0, [r10], #512
+        strd    r0, [r10, #512]