Index: test/TableGen/RegisterBankEmitter.td
===================================================================
--- /dev/null
+++ test/TableGen/RegisterBankEmitter.td
@@ -0,0 +1,15 @@
+// RUN: llvm-tblgen -gen-register-bank -I %p/../../include %s | FileCheck %s
+
+include "llvm/Target/Target.td"
+
+def MyTarget : Target;
+def R0 : Register<"r0">;
+// CHECK: GPRRegBankCoverageData
+// CHECK: 1u << (MyTarget::ClassARegClassID
+// CHECK: 1u << (MyTarget::ClassBRegClassID
+let Size = 32 in {
+  def ClassA : RegisterClass<"MyTarget", [i32], 32, (add R0)>;
+  def ClassB : RegisterClass<"MyTarget", [i1], 32, (add ClassA)>;
+}
+// CHECK: MyTarget::GPRRegBank
+def GPRRegBank : RegisterBank<"GPR", [ClassA]>;
Index: utils/TableGen/RegisterBankEmitter.cpp
===================================================================
--- utils/TableGen/RegisterBankEmitter.cpp
+++ utils/TableGen/RegisterBankEmitter.cpp
@@ -167,8 +167,14 @@
 ///                to the class.
 static void visitRegisterBankClasses(
     CodeGenRegBank &RegisterClassHierarchy, const CodeGenRegisterClass *RC,
-    const Twine Kind,
+    const Twine Kind, BitVector &Visited,
     std::function<void(const CodeGenRegisterClass *, StringRef)> VisitFn) {
+  if (Visited[RC->EnumValue]) {
+    DEBUG(dbgs() << "Not re-visiting " << RC->getName() << "\n");
+    return;
+  }
+  Visited[RC->EnumValue] = true;
+
   // Visit each explicitly named class.
   VisitFn(RC, Kind.str());
 
@@ -180,7 +186,7 @@
     if (RC != &PossibleSubclass && RC->hasSubClass(&PossibleSubclass))
       visitRegisterBankClasses(RegisterClassHierarchy, &PossibleSubclass,
                                TmpKind + " " + RC->getName() + " subclass",
-                               VisitFn);
+                               Visited, VisitFn);
 
     // Visit each class that contains only subregisters of RC with a common
     // subregister-index.
@@ -277,8 +283,9 @@
 
     for (const CodeGenRegisterClass *RC :
          Bank.getExplictlySpecifiedRegisterClasses(RegisterClassHierarchy)) {
+      BitVector Visited(RegisterClassHierarchy.getRegClasses().size());
       visitRegisterBankClasses(
-          RegisterClassHierarchy, RC, "explicit",
+          RegisterClassHierarchy, RC, "explicit", Visited,
           [&Bank](const CodeGenRegisterClass *RC, StringRef Kind) {
             DEBUG(dbgs() << "Added " << RC->getName() << "(" << Kind << ")\n");
             Bank.addRegisterClass(RC);