diff --git a/gcc/match.pd b/gcc/match.pd
index a9791ceb74a..827670fb59b 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -6147,6 +6147,24 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
    (floors tree_expr_nonnegative_p@0)
    (truncs @0))))
 
+/* Simplify,
+   erfc(x) -> 1 - erf(x) if canonicalize_math_p().
+   1 - erf(x) -> erfc(x) if !canonicalize_math_p().  */
+
+(if (flag_unsafe_math_optimizations)
+ (simplify
+  (ERFC @0)
+   (if (canonicalize_math_p ())
+    (minus { build_one_cst (TREE_TYPE (@0)); } (ERF @0))))
+ (simplify
+  (minus real_onep (ERF@1 @0))
+  (if (!canonicalize_math_p () && single_use (@1))
+   (ERFC @0))))
+ /* (x + 1) - erf(x) -> x + (1 - erf(x)).  */
+ (simplify
+  (minus (plus @0 real_onep) (ERF @0))
+  (plus @0 (minus { build_one_cst (TREE_TYPE (@0)); } (ERF @0))))
+
 (match double_value_p
  @0
  (if (TYPE_MAIN_VARIANT (TREE_TYPE (@0)) == double_type_node)))
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr83750-1.c b/gcc/testsuite/gcc.dg/tree-ssa/pr83750-1.c
new file mode 100644
index 00000000000..a1d456c0119
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr83750-1.c
@@ -0,0 +1,12 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -fdump-tree-optimized -funsafe-math-optimizations -fno-math-errno" } */
+
+double f(double x)
+{
+  double g (double, double);
+  double t1 = __builtin_erf (x);
+  double t2 = __builtin_erfc (x);
+  return g (t1, t2);
+}
+
+/* { dg-final { scan-tree-dump-not "__builtin_erfc" "optimized"} } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr83750-2.c b/gcc/testsuite/gcc.dg/tree-ssa/pr83750-2.c
new file mode 100644
index 00000000000..a55825bca47
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr83750-2.c
@@ -0,0 +1,9 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -fdump-tree-optimized -funsafe-math-optimizations -fno-math-errno" } */
+
+double f(double x)
+{
+  return __builtin_erfc (x); 
+}
+
+/* { dg-final { scan-tree-dump-not "__builtin_erf \\(" "optimized"} } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr83750-3.c b/gcc/testsuite/gcc.dg/tree-ssa/pr83750-3.c
new file mode 100644
index 00000000000..3305cdf125c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr83750-3.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -fdump-tree-optimized -funsafe-math-optimizations -fno-math-errno" } */
+
+double f1(double x)
+{
+  return x + __builtin_erfc (x); 
+}
+
+double f2(double x)
+{
+  return __builtin_erfc (x) + x;
+}
+
+/* { dg-final { scan-tree-dump-not "__builtin_erf \\(" "optimized"} } */