Index: llvm/include/llvm/Support/Errno.h
===================================================================
--- llvm/include/llvm/Support/Errno.h
+++ llvm/include/llvm/Support/Errno.h
@@ -34,9 +34,10 @@
 inline auto RetryAfterSignal(const FailT &Fail, const Fun &F,
                              const Args &... As) -> decltype(F(As...)) {
   decltype(F(As...)) Res;
-  do
+  do {
+    errno = 0;
     Res = F(As...);
-  while (Res == Fail && errno == EINTR);
+  } while (Res == Fail && errno == EINTR);
   return Res;
 }
 
Index: llvm/unittests/Support/ErrnoTest.cpp
===================================================================
--- llvm/unittests/Support/ErrnoTest.cpp
+++ llvm/unittests/Support/ErrnoTest.cpp
@@ -33,4 +33,7 @@
 
   std::unique_ptr<int> P(RetryAfterSignal(nullptr, [] { return new int(47); }));
   EXPECT_EQ(47, *P);
+
+  errno = EINTR;
+  EXPECT_EQ(-1, RetryAfterSignal(-1, [] { return -1; }));
 }