diff --git a/build/autoconf/toolchain.m4 b/build/autoconf/toolchain.m4
index 13b3ee158e03..e0e856ad4c47 100644
--- a/build/autoconf/toolchain.m4
+++ b/build/autoconf/toolchain.m4
@@ -35,31 +35,6 @@ if test "$CC_TYPE" = "clang-cl"; then
 fi
 ])
 
-AC_DEFUN([MOZ_TOOL_VARIABLES],
-[
-GNU_CC=
-GNU_CXX=
-if test "$CC_TYPE" = "gcc"; then
-    GNU_CC=1
-    GNU_CXX=1
-fi
-
-CLANG_CC=
-CLANG_CXX=
-CLANG_CL=
-if test "$CC_TYPE" = "clang"; then
-    GNU_CC=1
-    GNU_CXX=1
-    CLANG_CC=1
-    CLANG_CXX=1
-fi
-if test "$CC_TYPE" = "clang-cl"; then
-    CLANG_CL=1
-fi
-
-AC_SUBST(CLANG_CXX)
-AC_SUBST(CLANG_CL)
-])
 
 AC_DEFUN([MOZ_CROSS_COMPILER],
 [
diff --git a/js/src/old-configure.in b/js/src/old-configure.in
index 55151f64a003..cb7cc78500bf 100644
--- a/js/src/old-configure.in
+++ b/js/src/old-configure.in
@@ -78,8 +78,6 @@ else
     AC_PROG_CXX
 fi
 
-MOZ_TOOL_VARIABLES
-
 dnl Special win32 checks
 dnl ========================================================
 
diff --git a/old-configure.in b/old-configure.in
index a05ce64e3697..2d2ad0b6d3a7 100644
--- a/old-configure.in
+++ b/old-configure.in
@@ -69,8 +69,6 @@ else
     AC_PROG_CXX
 fi
 
-MOZ_TOOL_VARIABLES
-
 dnl ========================================================
 dnl Special win32 checks
 dnl ========================================================