diff --git a/compiler-rt/lib/msan/msan_interceptors.cpp b/compiler-rt/lib/msan/msan_interceptors.cpp
--- a/compiler-rt/lib/msan/msan_interceptors.cpp
+++ b/compiler-rt/lib/msan/msan_interceptors.cpp
@@ -827,7 +827,7 @@
 INTERCEPTOR(int, gethostname, char *name, SIZE_T len) {
   ENSURE_MSAN_INITED();
   int res = REAL(gethostname)(name, len);
-  if (!res) {
+  if (!res || (res == -1 && errno == errno_ENAMETOOLONG)) {
     SIZE_T real_len = REAL(strnlen)(name, len);
     if (real_len < len)
       ++real_len;
diff --git a/compiler-rt/lib/msan/tests/msan_test.cpp b/compiler-rt/lib/msan/tests/msan_test.cpp
--- a/compiler-rt/lib/msan/tests/msan_test.cpp
+++ b/compiler-rt/lib/msan/tests/msan_test.cpp
@@ -587,6 +587,20 @@
   return res;
 }
 
+TEST(MemorySanitizer, strcmp) {
+  char s1[10];
+  char s2[10];
+  strncpy(s1, "foo", 10);
+  s2[0] = 'f';
+  s2[1] = 'n';
+  EXPECT_GT(strcmp(s1, s2), 0);
+  s2[1] = 'o';
+  int res;
+  EXPECT_UMR(res = strcmp(s1, s2));
+  EXPECT_NOT_POISONED(res);
+  EXPECT_EQ(strncmp(s1, s2, 1), 0);
+}
+
 TEST(MemorySanitizer, LargeRet) {
   LargeStruct a = LargeRetTest();
   EXPECT_POISONED(a.x[0]);
@@ -1100,7 +1114,6 @@
   } while (0)
 
 TEST(MemorySanitizer, gethostent) {
-  sethostent(0);
   struct hostent *he = gethostent();
   ASSERT_NE((void *)NULL, he);
   EXPECT_HOSTENT_NOT_POISONED(he);
@@ -1164,7 +1177,6 @@
 
 #if !defined(__NetBSD__)
 TEST(MemorySanitizer, gethostent_r) {
-  sethostent(0);
   char buf[2000];
   struct hostent he;
   struct hostent *result;
@@ -3535,9 +3547,14 @@
 }
 
 TEST(MemorySanitizer, gethostname) {
-  char buf[100];
-  int res = gethostname(buf, 100);
-  ASSERT_EQ(0, res);
+  char buf[1000];
+  EXPECT_EQ(-1, gethostname(buf, 1));
+  EXPECT_EQ(ENAMETOOLONG, errno);
+  EXPECT_NOT_POISONED(buf[0]);
+  EXPECT_POISONED(buf[1]);
+
+  __msan_poison(buf, sizeof(buf));
+  EXPECT_EQ(0, gethostname(buf, sizeof(buf)));
   EXPECT_NOT_POISONED(strlen(buf));
 }
 
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_errno_codes.h b/compiler-rt/lib/sanitizer_common/sanitizer_errno_codes.h
--- a/compiler-rt/lib/sanitizer_common/sanitizer_errno_codes.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_errno_codes.h
@@ -24,6 +24,7 @@
 #define errno_ENOMEM 12
 #define errno_EBUSY 16
 #define errno_EINVAL 22
+#define errno_ENAMETOOLONG 36
 
 // Those might not present or their value differ on different platforms.
 extern const int errno_EOWNERDEAD;