Index: compiler-rt/test/fuzzer/windows-opt-ref.test
===================================================================
--- /dev/null
+++ compiler-rt/test/fuzzer/windows-opt-ref.test
@@ -0,0 +1,9 @@
+REQUIRES: windows
+// Verify that the linker eliminating unreferenced functions (/OPT:REF) does not
+// strip sancov module constructor.
+RUN: %cpp_compiler %S/SimpleCmpTest.cpp -o %t-SimpleCmpTest /link /OPT:REF
+
+RUN: not %run %t-SimpleCmpTest -seed=1 -runs=100000000 2>&1 | FileCheck %s
+
+CHECK-NOT: ERROR: no interesting inputs were found. Is the code instrumented for coverage? Exiting.
+CHECK: BINGO
Index: llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
===================================================================
--- llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
+++ llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
@@ -288,8 +288,11 @@
       M, SanCovModuleCtorName, InitFunctionName, {Ty, Ty},
       {SecStartPtr, IRB.CreatePointerCast(SecEnd, Ty)});
 
-  if (TargetTriple.supportsCOMDAT()) {
-    // Use comdat to dedup CtorFunc.
+  if (TargetTriple.supportsCOMDAT()&&
+      TargetTriple.getObjectFormat() != Triple::COFF) {
+    // Use comdat to dedup CtorFunc. Don't do it for COFF files since it will
+    // be stripped if linker strips unreferenced functions (ie: when linker flag
+    // "/OPT:REF" is used).
     CtorFunc->setComdat(M.getOrInsertComdat(SanCovModuleCtorName));
     appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority, CtorFunc);
   } else {