diff --git a/llvm/lib/CodeGen/MIRParser/MIParser.cpp b/llvm/lib/CodeGen/MIRParser/MIParser.cpp
index 389c5aaec8c70c..46ad8769fd3938 100644
--- a/llvm/lib/CodeGen/MIRParser/MIParser.cpp
+++ b/llvm/lib/CodeGen/MIRParser/MIParser.cpp
@@ -1077,7 +1077,7 @@ bool MIParser::parseOffset(int64_t &Offset) {
 bool MIParser::parseAlignment(unsigned &Alignment) {
   assert(Token.is(MIToken::kw_align));
   lex();
-  if (Token.isNot(MIToken::IntegerLiteral))
+  if (Token.isNot(MIToken::IntegerLiteral) || Token.integerValue().isSigned())
     return error("expected an integer literal after 'align'");
   if (getUnsigned(Alignment))
     return true;
diff --git a/llvm/test/CodeGen/MIR/X86/expected-positive-alignment-after-align.mir b/llvm/test/CodeGen/MIR/X86/expected-positive-alignment-after-align.mir
new file mode 100644
index 00000000000000..442d2fa7538924
--- /dev/null
+++ b/llvm/test/CodeGen/MIR/X86/expected-positive-alignment-after-align.mir
@@ -0,0 +1,32 @@
+# RUN: not llc -march=x86-64 -start-after branch-folder -stop-after branch-folder -o /dev/null %s 2>&1 | FileCheck %s
+
+--- |
+
+  define void @memory_alignment(<8 x float>* %vec) {
+  entry:
+    %v = load <8 x float>, <8 x float>* %vec
+    %v2 = insertelement <8 x float> %v, float 0.0, i32 4
+    store <8 x float> %v2, <8 x float>* %vec
+    ret void
+  }
+
+...
+---
+name:            memory_alignment
+tracksRegLiveness: true
+liveins:
+  - { reg: '%rdi' }
+body:
+  - id:          0
+    name:        entry
+    liveins:     [ '%rdi' ]
+    instructions:
+# CHECK: [[@LINE+1]]:76: expected an integer literal after 'align'
+      - '%xmm0 = MOVAPSrm %rdi, 1, _, 0, _ :: (load 16 from %ir.vec, align -32)'
+      - '%xmm1 = MOVAPSrm %rdi, 1, _, 16, _ :: (load 16 from %ir.vec + 16, align 32)'
+      - '%xmm2 = FsFLD0SS'
+      - '%xmm1 = MOVSSrr killed %xmm1, killed %xmm2'
+      - 'MOVAPSmr %rdi, 1, _, 0, _, killed %xmm0 :: (store 16 into %ir.vec, align 32)'
+      - 'MOVAPSmr killed %rdi, 1, _, 16, _, killed %xmm1 :: (store 16 into %ir.vec + 16, align 32)'
+      - RETQ
+...