diff --git a/lib/Target/ARM/AsmParser/ARMAsmParser.cpp b/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
index 2997c615a85..a0842b516ad 100644
--- a/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ b/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -9359,7 +9359,7 @@ unsigned ARMAsmParser::validateTargetOperandClass(MCParsedAsmOperand *AsmOp,
       const MCExpr *SOExpr = Op->getImm();
       int64_t Value;
       if (!SOExpr->EvaluateAsAbsolute(Value))
-        return Match_InvalidOperand;
+        return Match_Success;
       assert((Value >= INT32_MIN && Value <= INT32_MAX) &&
              "expression value must be representiable in 32 bits");
     }
diff --git a/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp b/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp
index 12cd33676a8..7ce9104ca7b 100644
--- a/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp
+++ b/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp
@@ -272,7 +272,25 @@ public:
   unsigned getSOImmOpValue(const MCInst &MI, unsigned Op,
                            SmallVectorImpl<MCFixup> &Fixups,
                            const MCSubtargetInfo &STI) const {
-    unsigned SoImm = MI.getOperand(Op).getImm();
+
+    const MCOperand &MO = MI.getOperand(Op);
+
+    // We expect MO to be an immediate or an expression,
+    // if it is an immediate - that's fine, just encode the value.
+    // Otherwise - create a Fixup.
+    if (MO.isExpr()) {
+      const MCExpr *Expr = MO.getExpr();
+      // In instruction code this value always encoded as lowest 12 bits,
+      // so we don't have to perform any specific adjustments.
+      // Due to requirements of relocatable records we have to use FK_Data_4.
+      // See ARMELFObjectWriter::ExplicitRelSym and
+      //     ARMELFObjectWriter::GetRelocTypeInner for more details.
+      MCFixupKind Kind = MCFixupKind(FK_Data_4);
+      Fixups.push_back(MCFixup::Create(0, Expr, Kind, MI.getLoc()));
+      return 0;
+    }
+
+    unsigned SoImm = MO.getImm();
     int SoImmVal = ARM_AM::getSOImmVal(SoImm);
     assert(SoImmVal != -1 && "Not a valid so_imm value!");
 
diff --git a/test/MC/ARM/cmp-immediate-fixup-error.s b/test/MC/ARM/cmp-immediate-fixup-error.s
new file mode 100644
index 00000000000..25a2368643d
--- /dev/null
+++ b/test/MC/ARM/cmp-immediate-fixup-error.s
@@ -0,0 +1,7 @@
+@ RUN: not llvm-mc -triple=arm-linux-gnueabi -filetype=obj < %s 2>&1 | FileCheck %s
+
+.text
+    cmp r0, #(l1 - unknownLabel + 4) >> 2
+@ CHECK: error: expected relocatable expression
+
+l1:
diff --git a/test/MC/ARM/cmp-immediate-fixup-error2.s b/test/MC/ARM/cmp-immediate-fixup-error2.s
new file mode 100644
index 00000000000..71f7fa141e0
--- /dev/null
+++ b/test/MC/ARM/cmp-immediate-fixup-error2.s
@@ -0,0 +1,7 @@
+@ RUN: not llvm-mc -triple=arm-linux-gnueabi -filetype=obj < %s 2>&1 | FileCheck %s
+
+.text
+    cmp r0, #(l1 - unknownLabel)
+@ CHECK: error: symbol 'unknownLabel' can not be undefined in a subtraction expression
+
+l1:
diff --git a/test/MC/ARM/cmp-immediate-fixup.s b/test/MC/ARM/cmp-immediate-fixup.s
new file mode 100644
index 00000000000..e21d5c20ccd
--- /dev/null
+++ b/test/MC/ARM/cmp-immediate-fixup.s
@@ -0,0 +1,9 @@
+@ PR18931
+@ RUN: llvm-mc < %s -triple=arm-linux-gnueabi -filetype=obj -o - \
+@ RUN: | llvm-objdump --disassemble -arch=arm - | FileCheck %s
+
+    .text
+@ CHECK: cmp r2, #1
+    cmp r2, #(l2 - l1 + 4) >> 2
+l1:
+l2:
diff --git a/test/MC/ARM/cmp-immediate-fixup2.s b/test/MC/ARM/cmp-immediate-fixup2.s
new file mode 100644
index 00000000000..c091145523c
--- /dev/null
+++ b/test/MC/ARM/cmp-immediate-fixup2.s
@@ -0,0 +1,9 @@
+@ PR18931
+@ RUN: llvm-mc < %s -triple=arm-linux-gnueabi -filetype=obj -o - \
+@ RUN: | llvm-objdump --disassemble -arch=arm - | FileCheck %s
+
+    .text
+@ CHECK: cmp r2, #0
+    cmp r2, #(l2 - l1)
+l1:
+l2:
diff --git a/test/MC/ARM/label_offset.s b/test/MC/ARM/label_offset.s
deleted file mode 100644
index 0aeb3b6ee69..00000000000
--- a/test/MC/ARM/label_offset.s
+++ /dev/null
@@ -1,8 +0,0 @@
-@ RUN: not llvm-mc -triple=armv7-linux-gnuabi -filetype=obj < %s 2>&1 | FileCheck %s
-
-.text
-    cmp r2, #(l2 - l1) >> 6
-@ CHECK: error: invalid operand for instruction
-
-l1:
-l2: