diff --git a/var/spack/repos/builtin/packages/icu4c/package.py b/var/spack/repos/builtin/packages/icu4c/package.py
index 175315ad1b2..f94fd66ebed 100644
--- a/var/spack/repos/builtin/packages/icu4c/package.py
+++ b/var/spack/repos/builtin/packages/icu4c/package.py
@@ -76,6 +76,10 @@ def flag_handler(self, name, flags):
             flags.append(getattr(self.compiler, f"cxx{self.spec.variants['cxxstd'].value}_flag"))
         return (None, flags, None)
 
+    @property
+    def libs(self):
+        return find_libraries("libicu*", root=self.prefix, recursive=True)
+
 
 class AutotoolsBuilder(spack.build_systems.autotools.AutotoolsBuilder):
 
diff --git a/var/spack/repos/builtin/packages/r/package.py b/var/spack/repos/builtin/packages/r/package.py
index cfd88312f44..b9004bf3119 100644
--- a/var/spack/repos/builtin/packages/r/package.py
+++ b/var/spack/repos/builtin/packages/r/package.py
@@ -232,6 +232,20 @@ def configure_args(self):
 
     @run_after("install")
     def copy_makeconf(self):
+        # Ensure full library flags are included in Makeconf
+        for _lib, _pkg in [
+            ("lzma", "xz"),
+            ("bz2", "bzip2"),
+            ("z", "zlib-api"),
+            ("tirpc", "libtirpc"),
+            ("icuuc", "icu4c"),
+        ]:
+            filter_file(
+                f"-l{_lib}",
+                f"-L{self.spec[_pkg].libs.directories[0]} -l{_lib}",
+                join_path(self.etcdir, "Makeconf"),
+            )
+
         # Make a copy of Makeconf because it will be needed to properly build R
         # dependencies in Spack.
         src_makeconf = join_path(self.etcdir, "Makeconf")