diff --git a/src/librustc_mir/borrow_check/places_conflict.rs b/src/librustc_mir/borrow_check/places_conflict.rs
index 24bd675fac2..9fbad46a238 100644
--- a/src/librustc_mir/borrow_check/places_conflict.rs
+++ b/src/librustc_mir/borrow_check/places_conflict.rs
@@ -15,6 +15,7 @@ use rustc::hir;
 use rustc::mir::{Mir, Place};
 use rustc::mir::{Projection, ProjectionElem};
 use rustc::ty::{self, TyCtxt};
+use std::cmp::max;
 
 pub(super) fn places_conflict<'gcx, 'tcx>(
     tcx: TyCtxt<'_, 'gcx, 'tcx>,
@@ -394,27 +395,77 @@ fn place_element_conflict<'a, 'gcx: 'tcx, 'tcx>(
                 | (ProjectionElem::Index(..), ProjectionElem::ConstantIndex { .. })
                 | (ProjectionElem::Index(..), ProjectionElem::Subslice { .. })
                 | (ProjectionElem::ConstantIndex { .. }, ProjectionElem::Index(..))
-                | (ProjectionElem::ConstantIndex { .. }, ProjectionElem::ConstantIndex { .. })
-                | (ProjectionElem::ConstantIndex { .. }, ProjectionElem::Subslice { .. })
-                | (ProjectionElem::Subslice { .. }, ProjectionElem::Index(..))
-                | (ProjectionElem::Subslice { .. }, ProjectionElem::ConstantIndex { .. })
-                | (ProjectionElem::Subslice { .. }, ProjectionElem::Subslice { .. }) => {
+                | (ProjectionElem::Subslice { .. }, ProjectionElem::Index(..)) => {
                     // Array indexes (`a[0]` vs. `a[i]`). These can either be disjoint
                     // (if the indexes differ) or equal (if they are the same), so this
                     // is the recursive case that gives "equal *or* disjoint" its meaning.
-                    //
-                    // Note that by construction, MIR at borrowck can't subdivide
-                    // `Subslice` accesses (e.g. `a[2..3][i]` will never be present) - they
-                    // are only present in slice patterns, and we "merge together" nested
-                    // slice patterns. That means we don't have to think about these. It's
-                    // probably a good idea to assert this somewhere, but I'm too lazy.
-                    //
-                    // FIXME(#8636) we might want to return Disjoint if
-                    // both projections are constant and disjoint.
-                    debug!("place_element_conflict: DISJOINT-OR-EQ-ARRAY");
+                    debug!("place_element_conflict: DISJOINT-OR-EQ-ARRAY-INDEX");
                     Overlap::EqualOrDisjoint
                 }
-
+                (ProjectionElem::ConstantIndex { offset: o1, min_length: _, from_end: false },
+                    ProjectionElem::ConstantIndex { offset: o2, min_length: _, from_end: false })
+                | (ProjectionElem::ConstantIndex { offset: o1, min_length: _, from_end: true },
+                    ProjectionElem::ConstantIndex {
+                        offset: o2, min_length: _, from_end: true }) => {
+                    if o1 == o2 {
+                        debug!("place_element_conflict: DISJOINT-OR-EQ-ARRAY-CONSTANT-INDEX");
+                        Overlap::EqualOrDisjoint
+                    } else {
+                        debug!("place_element_conflict: DISJOINT-ARRAY-CONSTANT-INDEX");
+                        Overlap::Disjoint
+                    }
+                }
+                (ProjectionElem::ConstantIndex {
+                    offset: offset_from_begin, min_length: min_length1, from_end: false },
+                    ProjectionElem::ConstantIndex {
+                        offset: offset_from_end, min_length: min_length2, from_end: true })
+                | (ProjectionElem::ConstantIndex {
+                    offset: offset_from_end, min_length: min_length1, from_end: true },
+                   ProjectionElem::ConstantIndex {
+                       offset: offset_from_begin, min_length: min_length2, from_end: false }) => {
+                    // both patterns matched so it must be at least the greater of the two
+                    let min_length = max(min_length1, min_length2);
+                    // offset_from_end can be in range [1..min_length], -1 for last and min_length
+                    // for first, min_length - offset_from_end gives minimal possible offset from
+                    // the beginning
+                    if *offset_from_begin >= min_length - offset_from_end {
+                        debug!("place_element_conflict: DISJOINT-OR-EQ-ARRAY-CONSTANT-INDEX-FE");
+                        Overlap::EqualOrDisjoint
+                    } else {
+                        debug!("place_element_conflict: DISJOINT-ARRAY-CONSTANT-INDEX-FE");
+                        Overlap::Disjoint
+                    }
+                }
+                (ProjectionElem::ConstantIndex { offset, min_length: _, from_end: false },
+                 ProjectionElem::Subslice {from, .. })
+                | (ProjectionElem::Subslice {from, .. },
+                    ProjectionElem::ConstantIndex { offset, min_length: _, from_end: false }) => {
+                    if offset >= from {
+                        debug!(
+                            "place_element_conflict: DISJOINT-OR-EQ-ARRAY-CONSTANT-INDEX-SUBSLICE");
+                        Overlap::EqualOrDisjoint
+                    } else {
+                        debug!("place_element_conflict: DISJOINT-ARRAY-CONSTANT-INDEX-SUBSLICE");
+                        Overlap::Disjoint
+                    }
+                }
+                (ProjectionElem::ConstantIndex { offset, min_length: _, from_end: true },
+                 ProjectionElem::Subslice {from: _, to })
+                | (ProjectionElem::Subslice {from: _, to },
+                    ProjectionElem::ConstantIndex { offset, min_length: _, from_end: true }) => {
+                    if offset > to {
+                        debug!("place_element_conflict: \
+                               DISJOINT-OR-EQ-ARRAY-CONSTANT-INDEX-SUBSLICE-FE");
+                        Overlap::EqualOrDisjoint
+                    } else {
+                        debug!("place_element_conflict: DISJOINT-ARRAY-CONSTANT-INDEX-SUBSLICE-FE");
+                        Overlap::Disjoint
+                    }
+                }
+                (ProjectionElem::Subslice { .. }, ProjectionElem::Subslice { .. }) => {
+                    debug!("place_element_conflict: DISJOINT-OR-EQ-ARRAY-SUBSLICES");
+                     Overlap::EqualOrDisjoint
+                }
                 (ProjectionElem::Deref, _)
                 | (ProjectionElem::Field(..), _)
                 | (ProjectionElem::Index(..), _)
diff --git a/src/test/run-pass/borrowck/borrowck-slice-pattern-element-loan.rs b/src/test/run-pass/borrowck/borrowck-slice-pattern-element-loan.rs
new file mode 100644
index 00000000000..48d16102ff3
--- /dev/null
+++ b/src/test/run-pass/borrowck/borrowck-slice-pattern-element-loan.rs
@@ -0,0 +1,33 @@
+// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//compile-flags: -Z borrowck=mir
+
+#![feature(slice_patterns)]
+
+fn mut_head_tail<'a, A>(v: &'a mut [A]) -> Option<(&'a mut A, &'a mut [A])> {
+    match *v {
+        [ref mut head, ref mut tail..] => {
+            Some((head, tail))
+        }
+        [] => None
+    }
+}
+
+fn main() {
+    let mut v = [1,2,3,4];
+    match mut_head_tail(&mut v) {
+        None => {},
+        Some((h,t)) => {
+            *h = 1000;
+            t.reverse();
+        }
+    }
+}
diff --git a/src/test/ui/borrowck/borrowck-slice-pattern-element-loan.rs b/src/test/ui/borrowck/borrowck-slice-pattern-element-loan.rs
new file mode 100644
index 00000000000..da36f494eb6
--- /dev/null
+++ b/src/test/ui/borrowck/borrowck-slice-pattern-element-loan.rs
@@ -0,0 +1,137 @@
+// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//compile-flags: -Z borrowck=mir
+
+#![feature(slice_patterns)]
+
+fn nop(_s: &[& i32]) {}
+fn nop_subslice(_s: &[i32]) {}
+
+fn const_index_ok(s: &mut [i32]) {
+    if let [ref first, ref second, _, ref fourth, ..] = *s {
+        if let [_, _, ref mut third, ..] = *s {
+            nop(&[first, second, third, fourth]);
+        }
+    }
+}
+
+fn const_index_err(s: &mut [i32]) {
+    if let [ref first, ref second, ..] = *s {
+        if let [_, ref mut  second2, ref mut third, ..] = *s { //~ERROR
+            nop(&[first, second, second2, third]);
+        }
+    }
+}
+
+fn const_index_from_end_ok(s: &mut [i32]) {
+    if let [.., ref fourth, ref third, _, ref first] = *s {
+        if let [.., ref mut second, _] = *s {
+            nop(&[first, second, third, fourth]);
+        }
+    }
+}
+
+fn const_index_from_end_err(s: &mut [i32]) {
+    if let [.., ref fourth, ref third, _, ref first] = *s {
+        if let [.., ref mut third2, _, _] = *s { //~ERROR
+            nop(&[first, third, third2, fourth]);
+        }
+    }
+}
+
+fn const_index_mixed(s: &mut [i32]) {
+    if let [.., _, ref from_end4, ref from_end3, _, ref from_end1] = *s {
+        if let [ref mut from_begin0, ..] = *s {
+            nop(&[from_begin0, from_end1, from_end3, from_end4]);
+        }
+        if let [_, ref mut from_begin1, ..] = *s { //~ERROR
+            nop(&[from_begin1, from_end1, from_end3, from_end4]);
+        }
+        if let [_, _, ref mut from_begin2, ..] = *s { //~ERROR
+            nop(&[from_begin2, from_end1, from_end3, from_end4]);
+        }
+        if let [_, _, _, ref mut from_begin3, ..] = *s { //~ERROR
+            nop(&[from_begin3, from_end1, from_end3, from_end4]);
+        }
+    }
+    if let [ref from_begin0, ref from_begin1, _, ref from_begin3, _, ..] = *s {
+        if let [.., ref mut from_end1] = *s {
+            nop(&[from_begin0, from_begin1, from_begin3, from_end1]);
+        }
+        if let [.., ref mut from_end2, _] = *s { //~ERROR
+            nop(&[from_begin0, from_begin1, from_begin3, from_end2]);
+        }
+        if let [.., ref mut from_end3, _,  _] = *s { //~ERROR
+            nop(&[from_begin0, from_begin1, from_begin3, from_end3]);
+        }
+        if let [.., ref mut from_end4, _, _, _] = *s { //~ERROR
+            nop(&[from_begin0, from_begin1, from_begin3, from_end4]);
+        }
+    }
+}
+
+fn const_index_and_subslice_ok(s: &mut [i32]) {
+    if let [ref first, ref second, ..] = *s {
+        if let [_, _, ref mut tail..] = *s {
+            nop(&[first, second]);
+            nop_subslice(tail);
+        }
+    }
+}
+
+fn const_index_and_subslice_err(s: &mut [i32]) {
+    if let [ref first, ref second, ..] = *s {
+        if let [_, ref mut tail..] = *s { //~ERROR
+            nop(&[first, second]);
+            nop_subslice(tail);
+        }
+    }
+}
+
+fn const_index_and_subslice_from_end_ok(s: &mut [i32]) {
+    if let [.., ref second, ref first] = *s {
+        if let [ref mut tail.., _, _] = *s {
+            nop(&[first, second]);
+            nop_subslice(tail);
+        }
+    }
+}
+
+fn const_index_and_subslice_from_end_err(s: &mut [i32]) {
+    if let [.., ref second, ref first] = *s {
+        if let [ref mut tail.., _] = *s { //~ERROR
+            nop(&[first, second]);
+            nop_subslice(tail);
+        }
+    }
+}
+
+fn subslices(s: &mut [i32]) {
+    if let [_, _, _, ref s1..] = *s {
+        if let [ref mut s2.., _, _, _] = *s { //~ERROR
+            nop_subslice(s1);
+            nop_subslice(s2);
+        }
+    }
+}
+
+fn main() {
+    let mut v = [1,2,3,4];
+    const_index_ok(&mut v);
+    const_index_err(&mut v);
+    const_index_from_end_ok(&mut v);
+    const_index_from_end_err(&mut v);
+    const_index_and_subslice_ok(&mut v);
+    const_index_and_subslice_err(&mut v);
+    const_index_and_subslice_from_end_ok(&mut v);
+    const_index_and_subslice_from_end_err(&mut v);
+    subslices(&mut v);
+}
diff --git a/src/test/ui/borrowck/borrowck-slice-pattern-element-loan.stderr b/src/test/ui/borrowck/borrowck-slice-pattern-element-loan.stderr
new file mode 100644
index 00000000000..16d401ec7f9
--- /dev/null
+++ b/src/test/ui/borrowck/borrowck-slice-pattern-element-loan.stderr
@@ -0,0 +1,119 @@
+error[E0502]: cannot borrow `s[..]` as mutable because it is also borrowed as immutable
+  --> $DIR/borrowck-slice-pattern-element-loan.rs:28:20
+   |
+LL |     if let [ref first, ref second, ..] = *s {
+   |                        ---------- immutable borrow occurs here
+LL |         if let [_, ref mut  second2, ref mut third, ..] = *s { //~ERROR
+   |                    ^^^^^^^^^^^^^^^^ mutable borrow occurs here
+LL |             nop(&[first, second, second2, third]);
+   |                          ------ borrow later used here
+
+error[E0502]: cannot borrow `s[..]` as mutable because it is also borrowed as immutable
+  --> $DIR/borrowck-slice-pattern-element-loan.rs:44:21
+   |
+LL |     if let [.., ref fourth, ref third, _, ref first] = *s {
+   |                             --------- immutable borrow occurs here
+LL |         if let [.., ref mut third2, _, _] = *s { //~ERROR
+   |                     ^^^^^^^^^^^^^^ mutable borrow occurs here
+LL |             nop(&[first, third, third2, fourth]);
+   |                          ----- borrow later used here
+
+error[E0502]: cannot borrow `s[..]` as mutable because it is also borrowed as immutable
+  --> $DIR/borrowck-slice-pattern-element-loan.rs:55:20
+   |
+LL |     if let [.., _, ref from_end4, ref from_end3, _, ref from_end1] = *s {
+   |                    ------------- immutable borrow occurs here
+...
+LL |         if let [_, ref mut from_begin1, ..] = *s { //~ERROR
+   |                    ^^^^^^^^^^^^^^^^^^^ mutable borrow occurs here
+LL |             nop(&[from_begin1, from_end1, from_end3, from_end4]);
+   |                                                      --------- borrow later used here
+
+error[E0502]: cannot borrow `s[..]` as mutable because it is also borrowed as immutable
+  --> $DIR/borrowck-slice-pattern-element-loan.rs:58:23
+   |
+LL |     if let [.., _, ref from_end4, ref from_end3, _, ref from_end1] = *s {
+   |                                   ------------- immutable borrow occurs here
+...
+LL |         if let [_, _, ref mut from_begin2, ..] = *s { //~ERROR
+   |                       ^^^^^^^^^^^^^^^^^^^ mutable borrow occurs here
+LL |             nop(&[from_begin2, from_end1, from_end3, from_end4]);
+   |                                           --------- borrow later used here
+
+error[E0502]: cannot borrow `s[..]` as mutable because it is also borrowed as immutable
+  --> $DIR/borrowck-slice-pattern-element-loan.rs:61:26
+   |
+LL |     if let [.., _, ref from_end4, ref from_end3, _, ref from_end1] = *s {
+   |                                   ------------- immutable borrow occurs here
+...
+LL |         if let [_, _, _, ref mut from_begin3, ..] = *s { //~ERROR
+   |                          ^^^^^^^^^^^^^^^^^^^ mutable borrow occurs here
+LL |             nop(&[from_begin3, from_end1, from_end3, from_end4]);
+   |                                           --------- borrow later used here
+
+error[E0502]: cannot borrow `s[..]` as mutable because it is also borrowed as immutable
+  --> $DIR/borrowck-slice-pattern-element-loan.rs:69:21
+   |
+LL |     if let [ref from_begin0, ref from_begin1, _, ref from_begin3, _, ..] = *s {
+   |                                                  --------------- immutable borrow occurs here
+...
+LL |         if let [.., ref mut from_end2, _] = *s { //~ERROR
+   |                     ^^^^^^^^^^^^^^^^^ mutable borrow occurs here
+LL |             nop(&[from_begin0, from_begin1, from_begin3, from_end2]);
+   |                                             ----------- borrow later used here
+
+error[E0502]: cannot borrow `s[..]` as mutable because it is also borrowed as immutable
+  --> $DIR/borrowck-slice-pattern-element-loan.rs:72:21
+   |
+LL |     if let [ref from_begin0, ref from_begin1, _, ref from_begin3, _, ..] = *s {
+   |                                                  --------------- immutable borrow occurs here
+...
+LL |         if let [.., ref mut from_end3, _,  _] = *s { //~ERROR
+   |                     ^^^^^^^^^^^^^^^^^ mutable borrow occurs here
+LL |             nop(&[from_begin0, from_begin1, from_begin3, from_end3]);
+   |                                             ----------- borrow later used here
+
+error[E0502]: cannot borrow `s[..]` as mutable because it is also borrowed as immutable
+  --> $DIR/borrowck-slice-pattern-element-loan.rs:75:21
+   |
+LL |     if let [ref from_begin0, ref from_begin1, _, ref from_begin3, _, ..] = *s {
+   |                              --------------- immutable borrow occurs here
+...
+LL |         if let [.., ref mut from_end4, _, _, _] = *s { //~ERROR
+   |                     ^^^^^^^^^^^^^^^^^ mutable borrow occurs here
+LL |             nop(&[from_begin0, from_begin1, from_begin3, from_end4]);
+   |                                ----------- borrow later used here
+
+error[E0502]: cannot borrow `s[..]` as mutable because it is also borrowed as immutable
+  --> $DIR/borrowck-slice-pattern-element-loan.rs:92:20
+   |
+LL |     if let [ref first, ref second, ..] = *s {
+   |                        ---------- immutable borrow occurs here
+LL |         if let [_, ref mut tail..] = *s { //~ERROR
+   |                    ^^^^^^^^^^^^ mutable borrow occurs here
+LL |             nop(&[first, second]);
+   |                          ------ borrow later used here
+
+error[E0502]: cannot borrow `s[..]` as mutable because it is also borrowed as immutable
+  --> $DIR/borrowck-slice-pattern-element-loan.rs:110:17
+   |
+LL |     if let [.., ref second, ref first] = *s {
+   |                 ---------- immutable borrow occurs here
+LL |         if let [ref mut tail.., _] = *s { //~ERROR
+   |                 ^^^^^^^^^^^^ mutable borrow occurs here
+LL |             nop(&[first, second]);
+   |                          ------ borrow later used here
+
+error[E0502]: cannot borrow `s[..]` as mutable because it is also borrowed as immutable
+  --> $DIR/borrowck-slice-pattern-element-loan.rs:119:17
+   |
+LL |     if let [_, _, _, ref s1..] = *s {
+   |                      ------ immutable borrow occurs here
+LL |         if let [ref mut s2.., _, _, _] = *s { //~ERROR
+   |                 ^^^^^^^^^^ mutable borrow occurs here
+LL |             nop_subslice(s1);
+   |                          -- borrow later used here
+
+error: aborting due to 11 previous errors
+
+For more information about this error, try `rustc --explain E0502`.