diff --git a/macros b/macros
index f062f94..bb8955f 100644
--- a/macros
+++ b/macros
@@ -136,7 +136,10 @@ print(result)
 %__cflags_arch_x86_64 %[0%{?rhel} >= 9 && "%{toolchain}" == "gcc" ? "-march=x86-64-v2" : ""]
 
 # Also used for s390.
-%__cflags_arch_s390x %[0%{?rhel} >= 8 ? "-march=z13 -mtune=z14" : "-march=zEC12 -mtune=z13"]
+%__cflags_arch_s390x %[0%{?rhel} >= 9 ? "-march=z14 -mtune=z15" : "-march=zEC12 -mtune=z13"]
+
+# Also used for ppc64le.
+%__cflags_arch_ppc64le %[0%{?rhel} >= 9 ? "-mcpu=power9 -mtune=power9" : "-mcpu=power8 -mtune=power8"]
 
 #==============================================================================
 # ---- configure and makeinstall.
diff --git a/redhat-rpm-config.spec b/redhat-rpm-config.spec
index bc0910d..5789533 100644
--- a/redhat-rpm-config.spec
+++ b/redhat-rpm-config.spec
@@ -6,7 +6,7 @@
 
 Summary: Red Hat specific rpm configuration files
 Name: redhat-rpm-config
-Version: 182
+Version: 183
 Release: 1%{?dist}
 # No version specified.
 License: GPL+
@@ -213,6 +213,10 @@ install -p -m 644 -t %{buildroot}%{_rpmluadir}/fedora/srpm forge.lua
 %{_rpmconfigdir}/macros.d/macros.kmp
 
 %changelog
+* Thu Apr 15 2021 Florian Weimer <fweimer@redhat.com> - 183-1
+- ppc64le: Update ISA baseline to POWER9 (#1876584)
+- s390x: Update ISA baseline to z14 (#1876479)
+
 * Mon Mar 22 2021 Lumír Balhar <lbalhar@redhat.com> - 182-1
 - Fix handling of files without newlines in brp-mangle-shebang
 
diff --git a/rpmrc b/rpmrc
index 12d5979..d59bc63 100644
--- a/rpmrc
+++ b/rpmrc
@@ -29,7 +29,7 @@ optflags: ppciseries %{__global_compiler_flags} -m32
 optflags: ppcpseries %{__global_compiler_flags} -m32
 optflags: ppc64 %{__global_compiler_flags} -m64 -fasynchronous-unwind-tables -fstack-clash-protection
 optflags: ppc64p7 %{__global_compiler_flags} -m64 -O3 -mcpu=power7 -mtune=power7 -fasynchronous-unwind-tables -fstack-clash-protection
-optflags: ppc64le %{__global_compiler_flags} -m64 -mcpu=power8 -mtune=power8 -fasynchronous-unwind-tables -fstack-clash-protection
+optflags: ppc64le %{__global_compiler_flags} -m64 %{__cflags_arch_ppc64le} -fasynchronous-unwind-tables -fstack-clash-protection
 optflags: ppc64iseries %{__global_compiler_flags} -m64
 optflags: ppc64pseries %{__global_compiler_flags} -m64
 optflags: ppc8260 %{__global_compiler_flags} -m32