diff --git a/compiler/rustc_codegen_llvm/src/llvm_util.rs b/compiler/rustc_codegen_llvm/src/llvm_util.rs
index a76c9c9b7356c..5b459cd18e307 100644
--- a/compiler/rustc_codegen_llvm/src/llvm_util.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm_util.rs
@@ -459,23 +459,25 @@ pub(crate) fn global_llvm_features(sess: &Session, diagnostics: bool) -> Vec<Str
     // Features that come earlier are overridden by conflicting features later in the string.
     // Typically we'll want more explicit settings to override the implicit ones, so:
     //
+    // * Features disabled by --target; are overridden by
     // * Features from -Ctarget-cpu=*; are overridden by [^1]
-    // * Features implied by --target; are overridden by
     // * Features from -Ctarget-feature; are overridden by
+    // * Features implied by --target; are overridden by
     // * function specific features.
     //
     // [^1]: target-cpu=native is handled here, other target-cpu values are handled implicitly
     // through LLVM TargetMachine implementation.
-    //
-    // FIXME(nagisa): it isn't clear what's the best interaction between features implied by
-    // `-Ctarget-cpu` and `--target` are. On one hand, you'd expect CLI arguments to always
-    // override anything that's implicit, so e.g. when there's no `--target` flag, features implied
-    // the host target are overridden by `-Ctarget-cpu=*`. On the other hand, what about when both
-    // `--target` and `-Ctarget-cpu=*` are specified? Both then imply some target features and both
-    // flags are specified by the user on the CLI. It isn't as clear-cut which order of precedence
-    // should be taken in cases like these.
     let mut features = vec![];
 
+    // Features disabled by an implicit or explicit `--target`.
+    features.extend(
+        sess.target
+            .features
+            .split(',')
+            .filter(|v| !v.is_empty() && backend_feature_name(v).is_some() && v.starts_with("-"))
+            .map(String::from),
+    );
+
     // -Ctarget-cpu=native
     match sess.opts.cg.target_cpu {
         Some(ref s) if s == "native" => {
@@ -501,15 +503,6 @@ pub(crate) fn global_llvm_features(sess: &Session, diagnostics: bool) -> Vec<Str
         Some(_) | None => {}
     };
 
-    // Features implied by an implicit or explicit `--target`.
-    features.extend(
-        sess.target
-            .features
-            .split(',')
-            .filter(|v| !v.is_empty() && backend_feature_name(v).is_some())
-            .map(String::from),
-    );
-
     // -Ctarget-features
     let supported_features = supported_target_features(sess);
     let mut featsmap = FxHashMap::default();
@@ -583,6 +576,15 @@ pub(crate) fn global_llvm_features(sess: &Session, diagnostics: bool) -> Vec<Str
         .flatten();
     features.extend(feats);
 
+    // Features implied by an implicit or explicit `--target`.
+    features.extend(
+        sess.target
+            .features
+            .split(',')
+            .filter(|v| !v.is_empty() && backend_feature_name(v).is_some() && v.starts_with("+"))
+            .map(String::from),
+    );
+
     if diagnostics && let Some(f) = check_tied_features(sess, &featsmap) {
         sess.emit_err(TargetFeatureDisableOrEnable {
             features: f,
diff --git a/compiler/rustc_target/src/spec/i386_apple_ios.rs b/compiler/rustc_target/src/spec/i386_apple_ios.rs
index 5819981612e84..0b51ccf44a5cb 100644
--- a/compiler/rustc_target/src/spec/i386_apple_ios.rs
+++ b/compiler/rustc_target/src/spec/i386_apple_ios.rs
@@ -17,6 +17,7 @@ pub fn target() -> Target {
         options: TargetOptions {
             max_atomic_width: Some(64),
             stack_probes: StackProbeType::X86,
+            features: "+x87".into(),
             ..opts("ios", arch)
         },
     }
diff --git a/compiler/rustc_target/src/spec/i386_unknown_linux_gnu.rs b/compiler/rustc_target/src/spec/i386_unknown_linux_gnu.rs
index 801a88933994a..c639bbabf569c 100644
--- a/compiler/rustc_target/src/spec/i386_unknown_linux_gnu.rs
+++ b/compiler/rustc_target/src/spec/i386_unknown_linux_gnu.rs
@@ -3,6 +3,7 @@ use crate::spec::Target;
 pub fn target() -> Target {
     let mut base = super::i686_unknown_linux_gnu::target();
     base.cpu = "i386".into();
+    base.features = "+x87".into();
     base.llvm_target = "i386-unknown-linux-gnu".into();
     base
 }
diff --git a/compiler/rustc_target/src/spec/i486_unknown_linux_gnu.rs b/compiler/rustc_target/src/spec/i486_unknown_linux_gnu.rs
index a11fbecc3c354..27b11e77c389f 100644
--- a/compiler/rustc_target/src/spec/i486_unknown_linux_gnu.rs
+++ b/compiler/rustc_target/src/spec/i486_unknown_linux_gnu.rs
@@ -3,6 +3,7 @@ use crate::spec::Target;
 pub fn target() -> Target {
     let mut base = super::i686_unknown_linux_gnu::target();
     base.cpu = "i486".into();
+    base.features = "+x87".into();
     base.llvm_target = "i486-unknown-linux-gnu".into();
     base
 }
diff --git a/compiler/rustc_target/src/spec/i586_pc_nto_qnx700.rs b/compiler/rustc_target/src/spec/i586_pc_nto_qnx700.rs
index 68afa7fe40127..d6c204cdd8b9a 100644
--- a/compiler/rustc_target/src/spec/i586_pc_nto_qnx700.rs
+++ b/compiler/rustc_target/src/spec/i586_pc_nto_qnx700.rs
@@ -11,6 +11,7 @@ pub fn target() -> Target {
         arch: "x86".into(),
         options: TargetOptions {
             cpu: "pentium4".into(),
+            features: "+x87".into(),
             max_atomic_width: Some(64),
             pre_link_args: TargetOptions::link_args(
                 LinkerFlavor::Gnu(Cc::Yes, Lld::No),
diff --git a/compiler/rustc_target/src/spec/i586_pc_windows_msvc.rs b/compiler/rustc_target/src/spec/i586_pc_windows_msvc.rs
index befb0f89f3b03..711c0b9c7ec41 100644
--- a/compiler/rustc_target/src/spec/i586_pc_windows_msvc.rs
+++ b/compiler/rustc_target/src/spec/i586_pc_windows_msvc.rs
@@ -3,6 +3,7 @@ use crate::spec::Target;
 pub fn target() -> Target {
     let mut base = super::i686_pc_windows_msvc::target();
     base.cpu = "pentium".into();
+    base.features = "+x87".into();
     base.llvm_target = "i586-pc-windows-msvc".into();
     base
 }
diff --git a/compiler/rustc_target/src/spec/i586_unknown_linux_gnu.rs b/compiler/rustc_target/src/spec/i586_unknown_linux_gnu.rs
index b699a7af17749..83ca39aed4caf 100644
--- a/compiler/rustc_target/src/spec/i586_unknown_linux_gnu.rs
+++ b/compiler/rustc_target/src/spec/i586_unknown_linux_gnu.rs
@@ -3,6 +3,7 @@ use crate::spec::Target;
 pub fn target() -> Target {
     let mut base = super::i686_unknown_linux_gnu::target();
     base.cpu = "pentium".into();
+    base.features = "+x87".into();
     base.llvm_target = "i586-unknown-linux-gnu".into();
     base
 }
diff --git a/compiler/rustc_target/src/spec/i586_unknown_linux_musl.rs b/compiler/rustc_target/src/spec/i586_unknown_linux_musl.rs
index 55a26eb004a7a..f8408debd912c 100644
--- a/compiler/rustc_target/src/spec/i586_unknown_linux_musl.rs
+++ b/compiler/rustc_target/src/spec/i586_unknown_linux_musl.rs
@@ -3,6 +3,7 @@ use crate::spec::Target;
 pub fn target() -> Target {
     let mut base = super::i686_unknown_linux_musl::target();
     base.cpu = "pentium".into();
+    base.features = "+x87".into();
     base.llvm_target = "i586-unknown-linux-musl".into();
     base
 }
diff --git a/compiler/rustc_target/src/spec/i686_apple_darwin.rs b/compiler/rustc_target/src/spec/i686_apple_darwin.rs
index b5103d15db695..f8e286c6fe942 100644
--- a/compiler/rustc_target/src/spec/i686_apple_darwin.rs
+++ b/compiler/rustc_target/src/spec/i686_apple_darwin.rs
@@ -5,6 +5,7 @@ pub fn target() -> Target {
     // ld64 only understands i386 and not i686
     let arch = Arch::I386;
     let mut base = opts("macos", arch);
+    base.features = "+x87,+sse,+sse2".into();
     base.max_atomic_width = Some(64);
     base.add_pre_link_args(LinkerFlavor::Darwin(Cc::Yes, Lld::No), &["-m32"]);
     base.stack_probes = StackProbeType::X86;
diff --git a/compiler/rustc_target/src/spec/i686_linux_android.rs b/compiler/rustc_target/src/spec/i686_linux_android.rs
index c7c30c23901d3..422fa006488d6 100644
--- a/compiler/rustc_target/src/spec/i686_linux_android.rs
+++ b/compiler/rustc_target/src/spec/i686_linux_android.rs
@@ -10,7 +10,7 @@ pub fn target() -> Target {
 
     // https://developer.android.com/ndk/guides/abis.html#x86
     base.cpu = "pentiumpro".into();
-    base.features = "+mmx,+sse,+sse2,+sse3,+ssse3".into();
+    base.features = "+x87,+mmx,+sse,+sse2,+sse3,+ssse3".into();
     base.stack_probes = StackProbeType::X86;
 
     Target {
diff --git a/compiler/rustc_target/src/spec/i686_pc_windows_gnu.rs b/compiler/rustc_target/src/spec/i686_pc_windows_gnu.rs
index 7a11138754fa8..e82a05d555064 100644
--- a/compiler/rustc_target/src/spec/i686_pc_windows_gnu.rs
+++ b/compiler/rustc_target/src/spec/i686_pc_windows_gnu.rs
@@ -3,6 +3,7 @@ use crate::spec::{Cc, FramePointer, LinkerFlavor, Lld, Target};
 pub fn target() -> Target {
     let mut base = super::windows_gnu_base::opts();
     base.cpu = "pentium4".into();
+    base.features = "+x87,+sse,+sse2".into();
     base.max_atomic_width = Some(64);
     base.frame_pointer = FramePointer::Always; // Required for backtraces
     base.linker = Some("i686-w64-mingw32-gcc".into());
diff --git a/compiler/rustc_target/src/spec/i686_pc_windows_gnullvm.rs b/compiler/rustc_target/src/spec/i686_pc_windows_gnullvm.rs
index 3154b512a5202..e8bff42dcb903 100644
--- a/compiler/rustc_target/src/spec/i686_pc_windows_gnullvm.rs
+++ b/compiler/rustc_target/src/spec/i686_pc_windows_gnullvm.rs
@@ -3,6 +3,7 @@ use crate::spec::{Cc, FramePointer, LinkerFlavor, Lld, Target};
 pub fn target() -> Target {
     let mut base = super::windows_gnullvm_base::opts();
     base.cpu = "pentium4".into();
+    base.features = "+x87,+sse,+sse2".into();
     base.max_atomic_width = Some(64);
     base.frame_pointer = FramePointer::Always; // Required for backtraces
     base.linker = Some("i686-w64-mingw32-clang".into());
diff --git a/compiler/rustc_target/src/spec/i686_pc_windows_msvc.rs b/compiler/rustc_target/src/spec/i686_pc_windows_msvc.rs
index db4c00dc697d7..f8e4e1f60b0d5 100644
--- a/compiler/rustc_target/src/spec/i686_pc_windows_msvc.rs
+++ b/compiler/rustc_target/src/spec/i686_pc_windows_msvc.rs
@@ -3,6 +3,7 @@ use crate::spec::{LinkerFlavor, Lld, Target};
 pub fn target() -> Target {
     let mut base = super::windows_msvc_base::opts();
     base.cpu = "pentium4".into();
+    base.features = "+x87,+sse,+sse2".into();
     base.max_atomic_width = Some(64);
 
     base.add_pre_link_args(
diff --git a/compiler/rustc_target/src/spec/i686_unknown_freebsd.rs b/compiler/rustc_target/src/spec/i686_unknown_freebsd.rs
index 35ca78034f170..ba8b325787027 100644
--- a/compiler/rustc_target/src/spec/i686_unknown_freebsd.rs
+++ b/compiler/rustc_target/src/spec/i686_unknown_freebsd.rs
@@ -3,6 +3,7 @@ use crate::spec::{Cc, LinkerFlavor, Lld, StackProbeType, Target};
 pub fn target() -> Target {
     let mut base = super::freebsd_base::opts();
     base.cpu = "pentium4".into();
+    base.features = "+x87,+sse,+sse2".into();
     base.max_atomic_width = Some(64);
     base.add_pre_link_args(LinkerFlavor::Gnu(Cc::Yes, Lld::No), &["-m32", "-Wl,-znotext"]);
     base.stack_probes = StackProbeType::X86;
diff --git a/compiler/rustc_target/src/spec/i686_unknown_haiku.rs b/compiler/rustc_target/src/spec/i686_unknown_haiku.rs
index e6b72336c5cf5..08827bfd323be 100644
--- a/compiler/rustc_target/src/spec/i686_unknown_haiku.rs
+++ b/compiler/rustc_target/src/spec/i686_unknown_haiku.rs
@@ -3,6 +3,7 @@ use crate::spec::{Cc, LinkerFlavor, Lld, StackProbeType, Target};
 pub fn target() -> Target {
     let mut base = super::haiku_base::opts();
     base.cpu = "pentium4".into();
+    base.features = "+x87,+sse,+sse2".into();
     base.max_atomic_width = Some(64);
     base.add_pre_link_args(LinkerFlavor::Gnu(Cc::Yes, Lld::No), &["-m32"]);
     base.stack_probes = StackProbeType::X86;
diff --git a/compiler/rustc_target/src/spec/i686_unknown_linux_gnu.rs b/compiler/rustc_target/src/spec/i686_unknown_linux_gnu.rs
index 73e536a7e4d93..b2bf7b757dcce 100644
--- a/compiler/rustc_target/src/spec/i686_unknown_linux_gnu.rs
+++ b/compiler/rustc_target/src/spec/i686_unknown_linux_gnu.rs
@@ -3,6 +3,7 @@ use crate::spec::{Cc, LinkerFlavor, Lld, SanitizerSet, StackProbeType, Target};
 pub fn target() -> Target {
     let mut base = super::linux_gnu_base::opts();
     base.cpu = "pentium4".into();
+    base.features = "+x87,+sse,+sse2".into();
     base.max_atomic_width = Some(64);
     base.supported_sanitizers = SanitizerSet::ADDRESS;
     base.add_pre_link_args(LinkerFlavor::Gnu(Cc::Yes, Lld::No), &["-m32"]);
diff --git a/compiler/rustc_target/src/spec/i686_unknown_linux_musl.rs b/compiler/rustc_target/src/spec/i686_unknown_linux_musl.rs
index 3825082ba25e4..a8a38837bc440 100644
--- a/compiler/rustc_target/src/spec/i686_unknown_linux_musl.rs
+++ b/compiler/rustc_target/src/spec/i686_unknown_linux_musl.rs
@@ -3,6 +3,7 @@ use crate::spec::{Cc, FramePointer, LinkerFlavor, Lld, StackProbeType, Target};
 pub fn target() -> Target {
     let mut base = super::linux_musl_base::opts();
     base.cpu = "pentium4".into();
+    base.features = "+x87,+sse,+sse2".into();
     base.max_atomic_width = Some(64);
     base.add_pre_link_args(LinkerFlavor::Gnu(Cc::Yes, Lld::No), &["-m32", "-Wl,-melf_i386"]);
     base.stack_probes = StackProbeType::X86;
diff --git a/compiler/rustc_target/src/spec/i686_unknown_netbsd.rs b/compiler/rustc_target/src/spec/i686_unknown_netbsd.rs
index b191996c7de0d..c6a41a08b7925 100644
--- a/compiler/rustc_target/src/spec/i686_unknown_netbsd.rs
+++ b/compiler/rustc_target/src/spec/i686_unknown_netbsd.rs
@@ -3,6 +3,7 @@ use crate::spec::{Cc, LinkerFlavor, Lld, StackProbeType, Target, TargetOptions};
 pub fn target() -> Target {
     let mut base = super::netbsd_base::opts();
     base.cpu = "pentium4".into();
+    base.features = "+x87,+sse,+sse2".into();
     base.max_atomic_width = Some(64);
     base.add_pre_link_args(LinkerFlavor::Gnu(Cc::Yes, Lld::No), &["-m32"]);
     base.stack_probes = StackProbeType::X86;
diff --git a/compiler/rustc_target/src/spec/i686_unknown_openbsd.rs b/compiler/rustc_target/src/spec/i686_unknown_openbsd.rs
index 8babe55971280..f383808798106 100644
--- a/compiler/rustc_target/src/spec/i686_unknown_openbsd.rs
+++ b/compiler/rustc_target/src/spec/i686_unknown_openbsd.rs
@@ -3,6 +3,7 @@ use crate::spec::{Cc, LinkerFlavor, Lld, StackProbeType, Target};
 pub fn target() -> Target {
     let mut base = super::openbsd_base::opts();
     base.cpu = "pentium4".into();
+    base.features = "+x87,+sse,+sse2".into();
     base.max_atomic_width = Some(64);
     base.add_pre_link_args(LinkerFlavor::Gnu(Cc::Yes, Lld::No), &["-m32", "-fuse-ld=lld"]);
     base.stack_probes = StackProbeType::X86;
diff --git a/compiler/rustc_target/src/spec/i686_uwp_windows_gnu.rs b/compiler/rustc_target/src/spec/i686_uwp_windows_gnu.rs
index a3e32569827fb..49ee4d9a5df68 100644
--- a/compiler/rustc_target/src/spec/i686_uwp_windows_gnu.rs
+++ b/compiler/rustc_target/src/spec/i686_uwp_windows_gnu.rs
@@ -3,6 +3,7 @@ use crate::spec::{Cc, FramePointer, LinkerFlavor, Lld, Target};
 pub fn target() -> Target {
     let mut base = super::windows_uwp_gnu_base::opts();
     base.cpu = "pentium4".into();
+    base.features = "+x87,+sse,+sse2".into();
     base.max_atomic_width = Some(64);
     base.frame_pointer = FramePointer::Always; // Required for backtraces
 
diff --git a/compiler/rustc_target/src/spec/i686_uwp_windows_msvc.rs b/compiler/rustc_target/src/spec/i686_uwp_windows_msvc.rs
index 4c657fe908ac4..c84162e4fb521 100644
--- a/compiler/rustc_target/src/spec/i686_uwp_windows_msvc.rs
+++ b/compiler/rustc_target/src/spec/i686_uwp_windows_msvc.rs
@@ -3,6 +3,7 @@ use crate::spec::Target;
 pub fn target() -> Target {
     let mut base = super::windows_uwp_msvc_base::opts();
     base.cpu = "pentium4".into();
+    base.features = "+x87,+sse,+sse2".into();
     base.max_atomic_width = Some(64);
 
     Target {
diff --git a/compiler/rustc_target/src/spec/i686_wrs_vxworks.rs b/compiler/rustc_target/src/spec/i686_wrs_vxworks.rs
index b5cfdfcebea90..0523d59e7f54f 100644
--- a/compiler/rustc_target/src/spec/i686_wrs_vxworks.rs
+++ b/compiler/rustc_target/src/spec/i686_wrs_vxworks.rs
@@ -3,6 +3,7 @@ use crate::spec::{Cc, LinkerFlavor, Lld, StackProbeType, Target};
 pub fn target() -> Target {
     let mut base = super::vxworks_base::opts();
     base.cpu = "pentium4".into();
+    base.features = "+x87,+sse,+sse2".into();
     base.max_atomic_width = Some(64);
     base.add_pre_link_args(LinkerFlavor::Gnu(Cc::Yes, Lld::No), &["-m32"]);
     base.stack_probes = StackProbeType::X86;