diff --git a/llvm/lib/Transforms/Utils/BuildLibCalls.cpp b/llvm/lib/Transforms/Utils/BuildLibCalls.cpp
--- a/llvm/lib/Transforms/Utils/BuildLibCalls.cpp
+++ b/llvm/lib/Transforms/Utils/BuildLibCalls.cpp
@@ -257,11 +257,19 @@
     Changed |= setDoesNotCapture(F, 1);
     Changed |= setOnlyReadsMemory(F, 0);
     return Changed;
-  case LibFunc_strcpy:
-  case LibFunc_strncpy:
   case LibFunc_strcat:
   case LibFunc_strncat:
+    Changed |= setOnlyAccessesArgMemory(F);
+    Changed |= setDoesNotThrow(F);
     Changed |= setWillReturn(F);
+    Changed |= setReturnedArg(F, 0);
+    Changed |= setDoesNotCapture(F, 1);
+    Changed |= setOnlyReadsMemory(F, 1);
+    Changed |= setDoesNotAlias(F, 0);
+    Changed |= setDoesNotAlias(F, 1);
+    return Changed;
+  case LibFunc_strcpy:
+  case LibFunc_strncpy:
     Changed |= setReturnedArg(F, 0);
     LLVM_FALLTHROUGH;
   case LibFunc_stpcpy:
diff --git a/llvm/test/Transforms/InferFunctionAttrs/annotate.ll b/llvm/test/Transforms/InferFunctionAttrs/annotate.ll
--- a/llvm/test/Transforms/InferFunctionAttrs/annotate.ll
+++ b/llvm/test/Transforms/InferFunctionAttrs/annotate.ll
@@ -839,7 +839,7 @@
 ; CHECK: declare i32 @strcasecmp(i8* nocapture, i8* nocapture) [[NOFREE_NOUNWIND_READONLY_WILLRETURN:#[0-9]+]]
 declare i32 @strcasecmp(i8*, i8*)
 
-; CHECK: declare i8* @strcat(i8* noalias returned writeonly, i8* noalias nocapture readonly) [[ARGMEMONLY_NOFREE_NOUNWIND_WILLRETURN]]
+; CHECK: declare i8* @strcat(i8* noalias returned, i8* noalias nocapture readonly) [[ARGMEMONLY_NOFREE_NOUNWIND_WILLRETURN]]
 declare i8* @strcat(i8*, i8*)
 
 ; CHECK: declare i8* @strchr(i8*, i32) [[ARGMEMONLY_NOFREE_NOUNWIND_READONLY]]
@@ -866,7 +866,7 @@
 ; CHECK: declare i32 @strncasecmp(i8* nocapture, i8* nocapture, i64) [[NOFREE_NOUNWIND_READONLY_WILLRETURN]]
 declare i32 @strncasecmp(i8*, i8*, i64)
 
-; CHECK: declare i8* @strncat(i8* noalias returned writeonly, i8* noalias nocapture readonly, i64) [[ARGMEMONLY_NOFREE_NOUNWIND_WILLRETURN]]
+; CHECK: declare i8* @strncat(i8* noalias returned, i8* noalias nocapture readonly, i64) [[ARGMEMONLY_NOFREE_NOUNWIND_WILLRETURN]]
 declare i8* @strncat(i8*, i8*, i64)
 
 ; CHECK: declare i32 @strncmp(i8* nocapture, i8* nocapture, i64) [[ARGMEMONLY_NOFREE_NOUNWIND_READONLY]]