Index: llvm/trunk/lib/Transforms/Instrumentation/MemorySanitizer.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Instrumentation/MemorySanitizer.cpp
+++ llvm/trunk/lib/Transforms/Instrumentation/MemorySanitizer.cpp
@@ -2918,8 +2918,11 @@
     if (ClDumpStrictInstructions)
       dumpInst(I);
     DEBUG(dbgs() << "DEFAULT: " << I << "\n");
-    for (size_t i = 0, n = I.getNumOperands(); i < n; i++)
-      insertShadowCheck(I.getOperand(i), &I);
+    for (size_t i = 0, n = I.getNumOperands(); i < n; i++) {
+      Value *Operand = I.getOperand(i);
+      if (Operand->getType()->isSized())
+        insertShadowCheck(Operand, &I);
+    }
     setShadow(&I, getCleanShadow(&I));
     setOrigin(&I, getCleanOrigin());
   }
Index: llvm/trunk/test/Instrumentation/MemorySanitizer/unsized_type.ll
===================================================================
--- llvm/trunk/test/Instrumentation/MemorySanitizer/unsized_type.ll
+++ llvm/trunk/test/Instrumentation/MemorySanitizer/unsized_type.ll
@@ -0,0 +1,22 @@
+; Check that unsized token types used by coroutine intrinsics do not cause
+; assertion failures.
+; RUN: opt < %s -msan -S 2>&1 | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+declare token @llvm.coro.id(i32, i8* readnone, i8* nocapture readonly, i8*)
+declare i1 @llvm.coro.alloc(token)
+
+define void @foo() sanitize_memory {
+entry:
+  %id = call token @llvm.coro.id(i32 0, i8* null, i8* null, i8* null)
+  %dyn.alloc.reqd = call i1  @llvm.coro.alloc(token %id)
+  ret void
+}
+
+; CHECK: define void @foo
+; CHECK-NEXT: entry:
+; CHECK-NEXT: %id = call token @llvm.coro.id
+; CHECK-NEXT: call i1 @llvm.coro.alloc(token %id)
+; CHECK-NEXT: ret void