Index: lib/CodeGen/MIRParser/MIParser.cpp
===================================================================
--- lib/CodeGen/MIRParser/MIParser.cpp
+++ lib/CodeGen/MIRParser/MIParser.cpp
@@ -1373,8 +1373,12 @@
 
   auto Loc = Token.location();
   lex();
-  if (Token.isNot(MIToken::IntegerLiteral))
-    return error("expected an integer literal");
+  if (Token.isNot(MIToken::IntegerLiteral)) {
+    if (Token.isNot(MIToken::Identifier) ||
+        !(Token.range().startswith("true") ||
+          Token.range().startswith("false")))
+      return error("expected an integer literal");
+  }
   const Constant *C = nullptr;
   if (parseIRConstant(Loc, C))
     return true;
Index: test/CodeGen/MIR/Generic/parse-integer-true-false.mir
===================================================================
--- /dev/null
+++ test/CodeGen/MIR/Generic/parse-integer-true-false.mir
@@ -0,0 +1,11 @@
+# RUN: llc -run-pass none -o - %s | FileCheck %s
+# Parse an i1 being a 'true' or 'false'
+---
+name: i1_true_false
+body: |
+  bb.0:
+    ; CHECK: %0:_(s1) = G_CONSTANT i1 true
+    ; CHECK: %1:_(s1) = G_CONSTANT i1 false
+    %0:_(s1) = G_CONSTANT i1 true
+    %1:_(s1) = G_CONSTANT i1 false
+...