diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index c9b6244125b..87126bd54e0 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2006-10-30  Kaveh R. Ghazi  <ghazi@caip.rutgers.edu>
+
+	PR middle-end/29335
+	* builtins.c (fold_builtin_1): Evaluate tgamma using MPFR.
+
 2006-10-30  Pete Steinmetz  <steinmtz@us.ibm.com>
 
 	* recog.c (store_data_bypass_p): Add support to allow IN_INSN to
diff --git a/gcc/builtins.c b/gcc/builtins.c
index 3a71e0462db..2184c714bdb 100644
--- a/gcc/builtins.c
+++ b/gcc/builtins.c
@@ -9121,6 +9121,12 @@ fold_builtin_1 (tree fndecl, tree arglist, bool ignore)
 			     NULL, NULL, 0);
     break;
 
+    CASE_FLT_FN (BUILT_IN_TGAMMA):
+      if (validate_arglist (arglist, REAL_TYPE, VOID_TYPE))
+	return do_mpfr_arg1 (TREE_VALUE (arglist), type, mpfr_gamma,
+			     NULL, NULL, 0);
+    break;
+ 
     CASE_FLT_FN (BUILT_IN_EXP):
       return fold_builtin_exponent (fndecl, arglist, mpfr_exp);
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index f9da3e8885b..1c6b906c3c1 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2006-10-30  Kaveh R. Ghazi  <ghazi@caip.rutgers.edu>
+
+	* gcc.dg/torture/builtin-math-2.c: Add tgamma tests.
+	* gcc.dg/torture/builtin-math-3.c: Likewise.
+
 2006-10-30  Tobias Burnus  <burnus@net-b.de>
 
 	PR fortran/29452
diff --git a/gcc/testsuite/gcc.dg/torture/builtin-math-2.c b/gcc/testsuite/gcc.dg/torture/builtin-math-2.c
index a2213da2f91..5b5d55a7d20 100644
--- a/gcc/testsuite/gcc.dg/torture/builtin-math-2.c
+++ b/gcc/testsuite/gcc.dg/torture/builtin-math-2.c
@@ -90,6 +90,13 @@ void bar()
   TESTIT (log1p, -2.0);
   TESTIT (log1p, -1.0);
 
+  /* The tgamma arg errors with zero or negative integers.  */
+  TESTIT (tgamma, 0.0);
+  TESTIT (tgamma, -0.0);
+  TESTIT (tgamma, -1.0);
+  TESTIT (tgamma, -2.0);
+  TESTIT (tgamma, -3.0);
+
   /* An argument of NaN is not evaluated at compile-time.  */
   foof (__builtin_powf (__builtin_nanf(""), 2.5F));
   foo (__builtin_pow (__builtin_nan(""), 2.5));
@@ -155,6 +162,9 @@ void bar()
 /* { dg-final { scan-tree-dump-times "log1p " 2 "original" } } */
 /* { dg-final { scan-tree-dump-times "log1pf" 2 "original" } } */
 /* { dg-final { scan-tree-dump-times "log1pl" 2 "original" } } */
+/* { dg-final { scan-tree-dump-times "tgamma " 5 "original" } } */
+/* { dg-final { scan-tree-dump-times "tgammaf" 5 "original" } } */
+/* { dg-final { scan-tree-dump-times "tgammal" 5 "original" } } */
 /* { dg-final { scan-tree-dump-times "pow " 13 "original" } } */
 /* { dg-final { scan-tree-dump-times "powf" 13 "original" } } */
 /* { dg-final { scan-tree-dump-times "powl" 13 "original" } } */
diff --git a/gcc/testsuite/gcc.dg/torture/builtin-math-3.c b/gcc/testsuite/gcc.dg/torture/builtin-math-3.c
index 3efe021d8db..34e02720eff 100644
--- a/gcc/testsuite/gcc.dg/torture/builtin-math-3.c
+++ b/gcc/testsuite/gcc.dg/torture/builtin-math-3.c
@@ -175,6 +175,21 @@ int main (void)
   TESTIT_R (erfc, 1.0, 0.15, 0.16); /* erfc(1) == 0.157... */
   TESTIT_R (erfc, -1.0, 1.84, 1.85); /* erfc(-1) == 1.842... */
 
+  TESTIT_R (tgamma, -4.5, -0.061, -0.060); /* tgamma(-4.5) == -0.06001... */
+  TESTIT_R (tgamma, -3.5, 0.27, 0.28); /* tgamma(-3.5) == 0.27008... */
+  TESTIT_R (tgamma, -2.5, -0.95, -0.94); /* tgamma(-2.5) == -0.945... */
+  TESTIT_R (tgamma, -1.5, 2.36, 2.37); /* tgamma(-1.5) == 2.363... */
+  TESTIT_R (tgamma, -0.5, -3.55, -3.54); /* tgamma(-0.5) == -3.544... */
+  TESTIT_R (tgamma, 0.5, 1.77, 1.78); /* tgamma(0.5) == 1.772... */
+  TESTIT (tgamma, 1.0, 1.0); /* tgamma(1) == 1 */
+  TESTIT_R (tgamma, 1.5, 0.88, 0.89); /* tgamma(1.5) == 0.886... */
+  TESTIT (tgamma, 2.0, 1.0); /* tgamma(2) == 1 */
+  TESTIT_R (tgamma, 2.5, 1.32, 1.33); /* tgamma(2.5) == 1.329... */
+  TESTIT (tgamma, 3.0, 2.0); /* tgamma(3) == 2 */
+  TESTIT_R (tgamma, 3.5, 3.32, 3.33); /* tgamma(3.5) == 3.323... */
+  TESTIT (tgamma, 4.0, 6.0); /* tgamma(4) == 6 */
+  TESTIT_R (tgamma, 4.5, 11.63, 11.64); /* tgamma(4.5) == 11.631... */
+
   TESTIT2 (pow, 3.0, 4.0, 81.0); /* pow(3,4) == 81 */
   TESTIT2 (pow, -3.0, 5.0, -243.0); /* pow(-3,5) == -243 */
   TESTIT2 (pow, 16.0, 0.25, 2.0); /* pow(16,1/4) == 2 */