Index: compiler-rt/trunk/lib/sanitizer_common/sanitizer_printf.cc
===================================================================
--- compiler-rt/trunk/lib/sanitizer_common/sanitizer_printf.cc
+++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_printf.cc
@@ -105,6 +105,8 @@
       break;
     result += AppendChar(buff, buff_end, *s);
   }
+  while (result < precision)
+    result += AppendChar(buff, buff_end, ' ');
   return result;
 }
 
Index: compiler-rt/trunk/lib/sanitizer_common/tests/sanitizer_printf_test.cc
===================================================================
--- compiler-rt/trunk/lib/sanitizer_common/tests/sanitizer_printf_test.cc
+++ compiler-rt/trunk/lib/sanitizer_common/tests/sanitizer_printf_test.cc
@@ -146,8 +146,13 @@
   EXPECT_EQ(3U, len);
   EXPECT_STREQ("123", buf);
   len = internal_snprintf(buf, sizeof(buf), "%.*s", 6, "12345");
-  EXPECT_EQ(5U, len);
-  EXPECT_STREQ("12345", buf);
+  EXPECT_EQ(6U, len);
+  EXPECT_STREQ("12345 ", buf);
+  // CHeck that precision does not overflow the smaller buffer, although
+  // 10 chars is requested, it stops at the buffer size, 8.
+  len = internal_snprintf(buf, 8, "%.*s", 10, "12345");
+  EXPECT_EQ(10U, len);  // The required size reported.
+  EXPECT_STREQ("12345  ", buf);
 }
 
 }  // namespace __sanitizer