diff --git a/llvm/lib/TableGen/Record.cpp b/llvm/lib/TableGen/Record.cpp
--- a/llvm/lib/TableGen/Record.cpp
+++ b/llvm/lib/TableGen/Record.cpp
@@ -459,7 +459,16 @@
 IntInit *IntInit::get(int64_t V) {
   static DenseMap<int64_t, IntInit*> ThePool;
 
-  IntInit *&I = ThePool[V];
+  // For any type you can use as the key in a DenseMap, there are two
+  // special values (called 'empty' and 'tombstone') which cannot be
+  // used as keys. Deal with those specially, to avoid an assertion
+  // failure if either one appears as an integer literal.
+  static IntInit *EmptyII = nullptr, *TombstoneII = nullptr;
+
+  IntInit *&I = (V == DenseMapInfo<int64_t>::getEmptyKey() ? EmptyII :
+                 V == DenseMapInfo<int64_t>::getTombstoneKey() ? TombstoneII :
+                 ThePool[V]);
+
   if (!I) I = new(Allocator) IntInit(V);
   return I;
 }
diff --git a/llvm/test/TableGen/IntSpecialValues.td b/llvm/test/TableGen/IntSpecialValues.td
new file mode 100644
--- /dev/null
+++ b/llvm/test/TableGen/IntSpecialValues.td
@@ -0,0 +1,8 @@
+// RUN: llvm-tblgen %s | FileCheck %s
+
+def TestRecord {
+  // CHECK: int X = 9223372036854775807;
+  int X = 0x7FFFFFFFFFFFFFFF;
+  // CHECK: int Y = 9223372036854775806;
+  int Y = 0x7FFFFFFFFFFFFFFE;
+}